Materials for organic light emitting devices

ABSTRACT

The present invention describes carbazole, dibenzofuran, dibenzothiophene and fluorene derivatives which are substituted by electron-deficient heteroaryl groups, in particular for use as triplet matrix materials in organic electroluminescent devices. The invention furthermore relates to a process for the preparation of the compounds according to the invention and to electronic devices comprising these compounds.

This application is a continuation of U.S. application Ser. No.16/808,515, filed Mar. 4, 2020, which is a continuation of U.S.application Ser. No. 15/308,749, filed Nov. 3, 2016, which is a Nationalstage application (under 35 U.S.C. § 371) of PCT/EP2015/000705, filedApr. 1, 2015, which claims benefit of European Application No.14001573.6, filed May 5, 2014, all of which are incorporated herein byreference in their entirety.

The present invention describes carbazole, dibenzofuran,dibenzothiophene and fluorene derivatives which are substituted byelectron-deficient heteroaromatic groups, in particular for use astriplet matrix materials in organic electroluminescent devices. Theinvention furthermore relates to a process for the preparation of thecompounds according to the invention and to electronic devicescomprising these compounds.

The structure of organic electroluminescent devices (OLEDs) in whichorganic semiconductors are employed as functional materials isdescribed, for example, in U.S. Pat. Nos. 4,539,507, 5,151,629, EP0676461 and WO 98/27136. The emitting materials employed are frequentlyorganometallic complexes which exhibit phosphorescence instead offluorescence. For quantum-mechanical reasons, an up to four-fold energyand power efficiency is possible using organometallic compounds asphosphorescence emitters. In general, there is still a need forimprovement, for example with respect to efficiency, operating voltageand lifetime, in the case of OLEDs, in particular also in the case ofOLEDs which exhibit phosphorescence.

The properties of phosphorescent OLEDs are not determined only by thetriplet emitters employed. In particular, the other materials used, suchas, for example, matrix materials, are also of particular importancehere. Improvements in these materials may thus also result insignificant improvements in the OLED properties.

In accordance with the prior art, use is made of, inter alia, carbazolederivatives (for example in accordance with WO 2014/015931),indolocarbazole derivatives (for example in accordance with WO2007/063754 or WO 2008/056746) or indenocarbazole derivatives (forexample in accordance with WO 2010/136109 or WO 2011/000455), inparticular those which are substituted by electron-deficientheteroaromatic compounds, such as triazine, as matrix materials forphosphorescent emitters. Furthermore, for example, bisdibenzofuranderivatives (for example in accordance with EP 2301926) are used asmatrix materials for phosphorescent emitters. WO 2011/057706 disclosescarbazole derivatives which are substituted by two triphenyltriazinegroups. Further improvements are still desirable here, in particularwith respect to the triplet level and to the sublimation stability. WO2011/046182 discloses carbazole-arylene-triazine derivatives which aresubstituted on the triazine by a fluorenyl group. The characteristicfeature of these compounds is the presence of the fluorenyl group.Compounds which do not contain a fluorenyl group as substituent are notdisclosed. WO 2013/077352 discloses triazine derivates in which thetriazine group is bonded to a dibenzofuran group via a divalent arylenegroup. These compounds are described as hole-blocking materials. A useof these materials as host for phosphorescent emitters is not described.

In general, there is still a need for improvement in these materials foruse as matrix materials, in particular with respect to the lifetime, butalso with respect to the efficiency and the operating voltage of thedevice.

The object of the present invention is the provision of compounds whichare suitable for use in a phosphorescent or fluorescent OLED, inparticular as matrix material. In particular, it is the object of thepresent invention to provide matrix materials which are suitable forred-, yellow- and green-phosphorescent OLEDs and optionally also forblue-phosphorescent OLEDs and which result in a long lifetime, goodefficiency and a low operating voltage. The properties of the matrixmaterials in particular also have an essential influence on the lifetimeand efficiency of the organic electroluminescent device.

Surprisingly, it has been found that electroluminescent devices whichcomprise compounds of the following formula (1) or formula (2) haveimprovements over the prior art, in particular on use as matrix materialfor phosphorescent dopants.

The present invention therefore relates to a compound of the followingformula (1) or (2),

where the following applies to the symbols and indices used:

-   -   A is on each occurrence, identically or differently, CR or N,        where a maximum of two groups A per ring, preferably a maximum        of one group A per ring, stand for N and where A stands for C if        a group L is bonded at this position;    -   W is on each occurrence, identically or differently, CR or N,        where a maximum of two groups W stand for N, or two adjacent        groups W together stand for a group of the following formula        (3), where the compound of the formula (1) or formula (2)        contains a maximum of one group of the formula (3),

where the dashed bonds indicate the linking of this group and A has themeanings given above; with the proviso that the compound of the formula(2) does not contain a group of the formula (3) if Y¹ stands for C(R)₂;

-   -   X is on each occurrence, identically or differently, CR or N,        with the proviso that at least one group X stands for N;    -   Ar is on each occurrence, identically or differently, an        aromatic or heteroaromatic ring system having 5 to 30 aromatic        ring atoms, which may be substituted by one or more radicals R;    -   Y¹, Y², Y³ are on each occurrence, identically or differently,        O, NR, S or C(R)₂, where the radical R which is bonded to N is        not equal to H;    -   L is on each occurrence, identically or differently, a single        bond or an aromatic or heteroaromatic ring system having 5 to 30        aromatic ring atoms, which may be substituted by one or more        radicals R;    -   R is selected on each occurrence, identically or differently,        from the group consisting of H, D, F, Cl, Br, I, CN, NO₂,        N(Ar¹)₂, N(R¹)₂, C(═O)Ar¹, C(═O)R¹, P(═O)(Ar¹)₂, P(Ar¹)₂,        B(Ar¹)₂, Si(Ar¹)₃, Si(R¹)₃, a straight-chain alkyl, alkoxy or        thioalkyl group having 1 to 20 C atoms or a branched or cyclic        alkyl, alkoxy or thioalkyl group having 3 to 20 C atoms or an        alkenyl group having 2 to 20 C atoms, each of which may be        substituted by one or more radicals R¹, where one or more        non-adjacent CH₂ groups may be replaced by R¹C≡CR¹, Si(R¹)₂,        C═O, C═S, C≡NR¹, P(═O)(R¹), SO, SO₂, NR¹, O, S or CONR¹ and        where one or more H atoms may be replaced by D, F, Cl, Br, I, CN        or NO₂, an aromatic or heteroaromatic ring system having 5 to 40        aromatic ring atoms, which may in each case be substituted by        one or more radicals R¹, an aryloxy or heteroaryloxy group        having 5 to 40 aromatic ring atoms, which may be substituted by        one or more radicals R¹, or an aralkyl or heteroaralkyl group        having 5 to 40 aromatic ring atoms, which may be substituted by        one or more radicals R¹; two substituents R which are bonded to        the same carbon atom or to adjacent carbon atoms may optionally        form a monocyclic or polycyclic, aliphatic, aromatic or        heteroaromatic ring system here, which may be substituted by one        or more radicals R¹;    -   Ar¹ is on each occurrence, identically or differently, an        aromatic or heteroaromatic ring system having 5 to 30 aromatic        ring atoms, which may be substituted by one or more non-aromatic        radicals R¹; two radicals Ar¹ which are bonded to the same N        atom, P atom or B atom may also be bridged to one another here        by a single bond or a bridge selected from N(R¹), C(R¹)₂, O or        S;    -   R¹ is selected on each occurrence, identically or differently,        from the group consisting of H, D, F, CN, an aliphatic        hydrocarbon radical having 1 to 20 C atoms or an aromatic or        heteroaromatic ring system having 5 to 30 aromatic ring atoms,        in which one or more H atoms may be replaced by D, F, Cl, Br, I        or CN and which may be substituted by one or more alkyl groups,        each having 1 to 4 carbon atoms; two or more adjacent        substituents R¹ may form a mono- or polycyclic, aliphatic ring        system with one another here.

Adjacent carbon atoms in the sense of the present invention are carbonatoms which are linked directly to one another.

The formulation that two or more radicals may form a ring with oneanother is, for the purposes of the present description, intended to betaken to mean, inter alia, that the two radicals are linked to oneanother by a chemical bond with formal cleaving-off of two hydrogenatoms. This is illustrated by the following scheme:

Furthermore, however, the above-mentioned formulation is also intendedto be taken to mean that, in the case where one of the two radicalsrepresents hydrogen, the second radical is bonded at the position atwhich the hydrogen atom was bonded, with formation of a ring. This isintended to be illustrated by the following scheme:

A condensed aryl group in the sense of the present invention is a groupin which two or more aromatic groups are condensed, i.e. annellated,onto one another via a common edge, such as, for example, innaphthalene. By contrast, for example, fluorene is not a condensed arylgroup in the sense of the present invention, since the two aromaticgroups in fluorene do not have a common edge.

An aryl group in the sense of this invention contains 6 to 40 C atoms; aheteroaryl group in the sense of this invention contains 2 to 40 C atomsand at least one heteroatom, with the proviso that the sum of C atomsand heteroatoms is at least 5. The heteroatoms are preferably selectedfrom N, O and/or S. An aryl group or heteroaryl group here is taken tomean either a simple aromatic ring, i.e. benzene, or a simpleheteroaromatic ring, for example pyridine, pyrimidine, thiophene, etc.,or a condensed aryl or heteroaryl group, for example naphthalene,anthracene, phenanthrene, quinoline, isoquinoline, etc.

An aromatic ring system in the sense of this invention contains 6 to 40C atoms in the ring system. A heteroaromatic ring system in the sense ofthis invention contains 1 to 40 C atoms and at least one heteroatom inthe ring system, with the proviso that the sum of C atoms andheteroatoms is at least 5. The heteroatoms are preferably selected fromN, O and/or S. An aromatic or heteroaromatic ring system in the sense ofthis invention is intended to be taken to mean a system which does notnecessarily contain only aryl or heteroaryl groups, but instead inwhich, in addition, a plurality of aryl or heteroaryl groups may beinterrupted by a non-aromatic unit (preferably less than 10% of theatoms other than H), such as, for example, a C, N or O atom or acarbonyl group. Thus, for example, systems such as 9,9′-spirobifluorene,9,9-diarylfluorene, triarylamine, diaryl ether, stilbene, etc., are alsointended to be taken to be aromatic ring systems in the sense of thisinvention, as are systems in which two or more aryl groups areinterrupted, for example, by a linear or cyclic alkyl group or by asilyl group. Furthermore, systems in which two or more aryl orheteroaryl groups are bonded directly to one another, such as, forexample, biphenyl, terphenyl, quaterphenyl or bipyridine, are likewiseintended to be taken to be an aromatic or heteroaromatic ring system.

A cyclic alkyl, alkoxy or thioalkoxy group in the sense of thisinvention is taken to mean a monocyclic, bicyclic or polycyclic group.

For the purposes of the present invention, a C₁- to C₂₀-alkyl group, inwhich, in addition, individual H atoms or CH₂ groups may be substitutedby the above-mentioned groups, is taken to mean, for example, theradicals methyl, ethyl, n-propyl, i-propyl, cyclopropyl, n-butyl,i-butyl, s-butyl, t-butyl, cyclobutyl, 2-methylbutyl, n-pentyl,s-pentyl, t-pentyl, 2-pentyl, neopentyl, cyclopentyl, n-hexyl, s-hexyl,t-hexyl, 2-hexyl, 3-hexyl, neohexyl, cyclo-hexyl, 1-methylcyclopentyl,2-methylpentyl, n-heptyl, 2-heptyl, 3-heptyl, 4-heptyl, cycloheptyl,1-methylcyclohexyl, n-octyl, 2-ethylhexyl, cyclooctyl,1-bicyclo[2.2.2]octyl, 2-bicyclo[2.2.2]octyl, 2-(2,6-dimethyl)octyl,3-(3,7-dimethyl)octyl, adamantyl, trifluoromethyl, pentafluoroethyl,2,2,2-trifluoro-ethyl, 1,1-dimethyl-n-hex-1-yl,1,1-dimethyl-n-hept-1-yl, 1,1-dimethyl-n-oct-1-yl,1,1-dimethyl-n-dec-1-yl, 1,1-dimethyl-n-dodec-1-yl,1,1-dimethyl-n-tetradec-1-yl, 1,1-dimethyl-n-hexadec-1-yl,1,1-dimethyl-n-octadec-1-yl, 1,1-diethyl-n-hex-1-yl,1,1-diethyl-n-hept-1-yl, 1,1-diethyl-n-oct-1-yl, 1,1-diethyl-n-dec-1-yl,1,1-diethyl-n-dodec-1-yl, 1,1-diethyl-n-tetradec-1-yl,1,1-diethyl-n-hexadec-1-yl, 1,1-diethyl-n-octadec-1-yl,1-(n-propyl)cyclohex-1-yl, 1-(n-butyl)cyclohex-1-yl,1-(n-hexyl)cyclohex-1-yl, 1-(n-octyl)cyclohex-1-yl and1-(n-decyl)cyclohex-1-yl. An alkenyl group is taken to mean, forexample, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl,cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl orcyclooctadienyl. An alkynyl group is taken to mean, for example,ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl or octynyl. AC₁- to C₄₀-alkoxy group is taken to mean, for example, methoxy,trifluoromethoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy,s-butoxy, t-butoxy or 2-methylbutoxy.

An aromatic or heteroaromatic ring system having 5-40 aromatic ringatoms, which may also in each case be substituted by the radicalsmentioned above and which may be linked to the aromatic orheteroaromatic ring system via any desired positions, is taken to mean,for example, groups derived from benzene, naphthalene, anthracene,benzanthracene, phenanthrene, benzophenanthrene, pyrene, chrysene,perylene, fluoranthene, benzofluoranthene, naphthacene, pentacene,benzopyrene, biphenyl, biphenylene, terphenyl, terphenylene, fluorene,spirobifluorene, dihydrophenanthrene, dihydropyrene, tetrahydropyrene,cis- or trans-indenofluorene, trans-monobenzoindenofluorene, cis- ortrans-dibenzo-indenofluorene, truxene, isotruxene, spirotruxene,spiroisotruxene, furan, benzofuran, isobenzofuran, dibenzofuran,thiophene, benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole,indole, isoindole, carbazole, indolocarbazole, indenocarbazole,pyridine, quinoline, isoquinoline, acridine, phenanthridine,benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline,phenothiazine, phenoxazine, pyrazole, indazole, imidazole,benzimidazole, naphthimidazole, phenanthrimidazole, pyridimidazole,pyrazinimidazole, quinoxalinimidazole, oxazole, benzoxazole,naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, 1,2-thiazole,1,3-thiazole, benzothiazole, pyridazine, benzopyridazine, pyrimidine,benzopyrimidine, quinoxaline, 1,5-diazaanthracene, 2,7-diazapyrene,2,3-diazapyrene, 1,6-diazapyrene, 1,8-diazapyrene, 4,5-diazapyrene,4,5,9,10-tetraaza-perylene, pyrazine, phenazine, phenoxazine,phenothiazine, fluorubin, naphthyridine, azacarbazole, benzocarboline,phenanthroline, 1,2,3-triazole, 1,2,4-triazole, benzotriazole,1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole,1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole,1,3,4-thiadiazole, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine,tetrazole, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine,purine, pteridine, indolizine and benzothiadiazole.

In a preferred embodiment of the invention, W stands, identically ordifferently on each occurrence, for CR or two W stand for a group of theformula (3a) and the remaining W stand for CR, and A stands, identicallyor differently on each occurrence, for CR. Preference is thus given tothe compounds of the following formulae (1a), (1b), (2a) and (2b),

where:

-   -   two adjacent groups W together stand for a group of the        following formula (3a) and the other two groups W stand for CR        and preferably for CH,

where the dashed bonds indicate the linking of this group;

-   -   n is on each occurrence, identically or differently, 0, 1, 2, 3        or 4;    -   m is on each occurrence, identically or differently, 0, 1, 2 or        3;    -   is 0, 1 or 2;    -   the other symbols used have the meanings given above;    -   where compounds of the formula (2b) in which Y¹ stands for CR₂        are excluded from the invention.

In a preferred embodiment of the invention, at least two groups X standfor N, and the group X optionally remaining stands for CR, in particularfor CH. In a particularly preferred embodiment of the invention, allgroups X stand for N. It is thus particularly preferably adiaryltriazine group.

In a preferred embodiment of the invention, the following group,

which is bonded in formulae (1) and (2) or the preferred embodiments istherefore selected from the following groups (HetAr-1), (HetAr-2) or(HetAr-3),

where L and Ar have the meanings given above and the dashed bondindicates the linking of this group.

In a further preferred embodiment of the invention, Y¹ and Y² stand,identically or differently on each occurrence, for O, NR, where theradical R bonded to the nitrogen is not equal to H, or S. It ispreferred here for at least one of the groups Y¹ and/or Y² to stand forNR and for Y¹ in formula (2) to stand for O or S. In a particularlypreferred embodiment of the invention, Y¹ and Y² stand, identically ordifferently, for O or NR, where the radical R bonded to the nitrogen isnot equal to H, where Y¹ and Y² are preferably different. Veryparticularly preferably, Y¹ stands for O and Y² stands for NR, where theradical R bonded to the nitrogen is not equal to H.

In a further preferred embodiment of the invention, Y³, if the compoundcontains a group of the formula (3), stands for O, NR, where the radicalR bonded to the nitrogen is not equal to H, or C(R)₂, particularlypreferably for NR, where the radical R bonded to the nitrogen is notequal to H, or C(R)₂ and very particularly preferably for C(R)₂.

If the compound according to the invention contains a group of theformula (3), this can be bonded in various positions. This is depicteddiagrammatically below by the formulae (A) to (F) with reference topreferred embodiments in which the groups A and the other groups W standfor CR:

where the symbols and indices used have the meanings given above and thedashed bond represents the linking in the compound according to theinvention.

In a further preferred embodiment of the invention, L stands,identically or differently on each occurrence, for a single bond or anaromatic or heteroaromatic ring system having 5 to 24 aromatic ringatoms, which may be substituted by one or more radicals R. Lparticularly preferably stands, identically or differently on eachoccurrence, for a single bond or an aromatic ring system having 6 to 12aromatic ring atoms or a heteroaromatic ring system having 6 to 13aromatic ring atoms, which may in each case be substituted by one ormore radicals R, but is preferably unsubstituted. L very particularlypreferably stands for a single bond. Examples of suitable aromatic orheteroaromatic ring systems L are selected from the group consisting ofortho-, meta- or para-phenylene, biphenyl, fluorene, pyridine,pyrimidine, triazine, dibenzofuran, dibenzothiophene and carbazole, eachof which may be substituted by one or more radicals R, but is preferablyunsubstituted.

In a further preferred embodiment of the invention, Ar stands,identically or differently on each occurrence, for an aromatic orheteroaromatic ring system having 6 to 24 aromatic ring atoms,preferably having 6 to 18 aromatic ring atoms, particularly preferablyfor an aromatic ring system having 6 to 12 aromatic ring atoms or aheteroaromatic ring system having 6 to 13 aromatic ring atoms, which mayin each case be substituted by one or more radicals R, but is preferablyunsubstituted. Examples of suitable groups Ar are selected from thegroup consisting of phenyl, ortho-, meta- or para-biphenyl, terphenyl,in particular branched terphenyl, quaterphenyl, in particular branchedquaterphenyl, 1-, 2-, 3- or 4-fluorenyl, 1-, 2-, 3- or4-spirobifluorenyl, pyridyl, pyrimidinyl, 1-, 2-, 3- or4-dibenzofuranyl, 1-, 2-, 3- or 4-dibenzothienyl and 1-, 2-, 3- or4-carbazolyl, each of which may be substituted by one or more radicalsR, but is preferably unsubstituted.

Examples of suitable groups Ar are the structures Ar-1 to Ar-19 shownbelow,

where Y³ and R have the meanings given above and the dashed bondrepresents the bond to the six-membered heteroaryl ring group in formula(1) or formula (2).

In a further preferred embodiment of the invention, the index n incompounds of the formula (1a) or (2a) is 0, 1, 2 or 3, particularlypreferably 0, 1 or 2 and very particularly preferably 0 or 1.

In still a further preferred embodiment of the invention, the index m incompounds of the formula (1a) or (2a) is 0, 1 or 2, particularlypreferably 0 or 1 and very particularly preferably 0.

In still a further preferred embodiment of the invention, the index o incompounds of the formula (1a) or (2a) is 0 or 1, particularly preferably0.

Preferred substituents R are described below. The preferred substituentshere depend on whether they are bonded to A or W or to Ar or to Y¹, Y²or Y³ and also depend on how Y¹, Y² and Y³ are selected.

If A stands for CR or if W stands for CR or if the groups Ar aresubstituted by substituents R, these substituents R are then preferablyselected from the group consisting of H, D, F, CN, N(Ar¹)₂, C(═O)Ar¹,P(═O)(Ar¹)₂, a straight-chain alkyl or alkoxy group having 1 to 10 Catoms or a branched or cyclic alkyl or alkoxy group having 3 to 10 Catoms or an alkenyl group having 2 to 10 C atoms, each of which may besubstituted by one or more radicals R¹, where one or more non-adjacentCH₂ groups may be replaced by O and where one or more H atoms may bereplaced by D or F, an aromatic or heteroaromatic ring system having 5to 24 aromatic ring atoms, which may in each case be substituted by oneor more radicals R¹, but is preferably unsubstituted, or an aralkyl orheteroaralkyl group having 5 to 25 aromatic ring atoms, which may besubstituted by one or more radicals R¹; two substituents R which arebonded to the same carbon atom or to adjacent carbon atoms mayoptionally form a monocyclic or polycyclic, aliphatic, aromatic orheteroaromatic ring system here, which may be substituted by one or moreradicals R¹.

These substituents R are particularly preferably selected from the groupconsisting of H, D, F, CN, N(Ar¹)₂, a straight-chain alkyl group having1 to 8 C atoms, preferably having 1, 2, 3 or 4 C atoms, or a branched orcyclic alkyl group having 3 to 8 C atoms, preferably having 3 or 4 Catoms, or an alkenyl group having 2 to 8 C atoms, preferably having 2, 3or 4 C atoms, each of which may be substituted by one or more radicalsR¹, but is preferably unsubstituted, or an aromatic or heteroaromaticring system having 6 to 24 aromatic ring atoms, preferably having 6 to18 aromatic ring atoms, particularly preferably having 6 to 13 aromaticring atoms, which may in each case be substituted by one or morenon-aromatic radicals R¹, but is preferably unsubstituted; twosubstituents R which are bonded to the same carbon atom or to adjacentcarbon atoms may optionally form a monocyclic or polycyclic, aliphaticring system here, which may be substituted by one or more radicals R¹,but is preferably unsubstituted.

The substituents R are very particularly preferably selected from thegroup consisting of H or an aromatic or heteroaromatic ring systemhaving 6 to 18 aromatic ring atoms, preferably having 6 to 13 aromaticring atoms, which may in each case be substituted by one or morenon-aromatic radicals R¹, but is preferably unsubstituted. Examples ofsuitable substituents R are selected from the group consisting ofphenyl, ortho-, meta- or para-biphenyl, terphenyl, in particularbranched terphenyl, quaterphenyl, in particular branched quaterphenyl,1-, 2-, 3- or 4-fluorenyl, 1-, 2-, 3- or 4-spirobifluorenyl, pyridyl,pyrimidinyl, 1-, 2-, 3- or 4-dibenzofuranyl, 1-, 2-, 3- or4-dibenzothienyl and 1-, 2-, 3- or 4-carbazolyl, each of which may besubstituted by one or more radicals R¹, but is preferably unsubstituted.Suitable structures R here are the same structures as depicted above forAr-1 to Ar-19, where these structures are substituted by R¹ instead ofR. For substituents R on the groups Ar, apart from the groups mentionedabove, straight-chain alkyl groups having 1 to 4 C atoms or branched orcyclic alkyl groups having 3 to 6 C atoms are also particularlypreferred.

If Y¹ or Y² or Y³ stands for NR, the radical R which is bonded to thisnitrogen atom preferably stands on each occurrence, identically ordifferently, for an aromatic or heteroaromatic ring system having 5 to24 aromatic ring atoms, which may in each case be substituted by one ormore radicals R¹, particularly preferably for an aromatic orheteroaromatic ring system having 6 to 18 aromatic ring atoms, which maybe substituted by one or more radicals R¹. Examples of suitablesubstituents R are selected from the group consisting of phenyl, ortho-,meta- or para-biphenyl, terphenyl, in particular branched terphenyl,quaterphenyl, in particular branched quaterphenyl, 1-, 2-, 3- or4-fluorenyl, 1-, 2-, 3- or 4-spirobifluorenyl, pyridyl, pyrimidinyl,1,3,5-triazinyl, 4,6-diphenyl-1,3,5-triazinyl, 1-, 2-, 3- or4-dibenzofuranyl, 1-, 2-, 3- or 4-dibenzothienyl and 1-, 2-, 3- or4-carbazolyl, where the carbazolyl group is substituted on the nitrogenatom by a radical R¹ which is not equal to H or D. These groups may eachbe substituted by one or more radicals R¹ here, but are preferablyunsubstituted. Suitable structures R here are the same structures asdepicted above for Ar-1 to Ar-19, where these structures are substitutedby R¹ instead of R.

If Y¹ or Y² or Y³ stands for C(R)₂, the radicals R which are bonded tothis carbon atom preferably stand on each occurrence, identically ordifferently, for a straight-chain alkyl group having 1 to 10 C atoms ora branched or cyclic alkyl group having 3 to 10 C atoms or an alkenylgroup having 2 to 10 C atoms, each of which may be substituted by one ormore radicals R¹, where one or more non-adjacent CH₂ groups may bereplaced by O and where one or more H atoms may be replaced by D or F,or for an aromatic or heteroaromatic ring system having 5 to 24 aromaticring atoms, which may in each case be substituted by one or moreradicals R¹; the two substituents R may optionally form a monocyclic orpolycyclic, aliphatic, aromatic or heteroaromatic ring system here,which may be substituted by one or more radicals R¹. Ring formation ofthe two substituents R forms a spiro system, for example aspirobifluorene or a derivative of a spirobifluorene, if the groups Rstand for phenyl groups.

In a further preferred embodiment of the invention, R¹ is selected oneach occurrence, identically or differently, from the group consistingof H, D, F, CN, an aliphatic hydrocarbon radical having 1 to 10 C atoms,preferably having 1, 2, 3 or 4 C atoms, or an aromatic or heteroaromaticring system having 5 to 30 aromatic ring atoms, preferably having 5 to24 aromatic ring atoms, particularly preferably having 5 to 13 aromaticring atoms, which may be substituted by one or more alkyl groups, eachhaving 1 to 4 carbon atoms, but is preferably unsubstituted.

If the compound according to the invention is substituted by aromatic orheteroaromatic groups R or R¹ or Ar or Ar¹, these preferably contain noaryl or heteroaryl groups having more than two aromatic six-memberedrings condensed directly onto one another. The substituents particularlypreferably contain absolutely no aryl or heteroaryl groups havingsix-membered rings condensed directly onto one another. This preferenceis due to the low triplet energy of such structures. Condensed arylgroups having more than two aromatic six-membered rings condenseddirectly onto one another which are nevertheless also suitable inaccordance with the invention are phenanthrene and triphenylene, sincethese also have a high triplet level.

The preferences indicated above may occur individually or together. Thepreferences indicated above preferably occur together.

Preference is thus given to compounds of the above-mentioned formulae(1), (2), (1a), (1b), (2a) and (2b) for which:

-   -   X is, identically or differently on each occurrence, CR or N,        where at least two groups X stand for N and any remaining group        X stands for CR, in particular for CH;    -   Y¹, Y² stand, identically or differently on each occurrence, for        O, NR, where the radical R bonded to the nitrogen is not equal        to H, or S; preferably, at least one of the groups Y¹ and/or Y²        stands for NR and    -   Y³ in formulae (2), (2a) and (2b) stands for O or S here; Y³        stands for O, NR, where the radical R bonded to the nitrogen is        not equal to H, or CR₂;    -   L stands, identically or differently on each occurrence, for a        single bond or an aromatic or heteroaromatic ring system having        5 to 24 aromatic ring atoms, in particular having 6 to 12        aromatic ring atoms, which may be substituted by one or more        radicals R, but is preferably unsubstituted;    -   Ar stands, identically or differently on each occurrence, for an        aromatic or heteroaromatic ring system having 6 to 24 aromatic        ring atoms, which may be substituted by one or more radicals R,        but is preferably unsubstituted;    -   n in formula (1a), (1b), (2a) or (2b) is, identically or        differently on each occurrence, 0, 1, 2 or 3, preferably 0, 1 or        2;    -   m in formula (1a), (1b), (2a) or (2b) is, identically or        differently on each occurrence, 0, 1 or 2, preferably 0 or 1;    -   in formula (1a), (1b), (2a) or (2b) is 0 or 1;    -   R is selected, identically or differently on each occurrence,        from the group consisting of H, D, F, CN, N(Ar¹)₂, C(═O)Ar¹,        P(═O)(Ar¹)₂, a straight-chain alkyl or alkoxy group having 1 to        10 C atoms or a branched or cyclic alkyl or alkoxy group having        3 to 10 C atoms or an alkenyl group having 2 to 10 C atoms, each        of which may be substituted by one or more radicals R¹, where        one or more non-adjacent CH₂ groups may be replaced by O and        where one or more H atoms may be replaced by D or F, an aromatic        or heteroaromatic ring system having 5 to 24 aromatic ring        atoms, which may in each case be substituted by one or more        radicals R¹, or an aralkyl or heteroaralkyl group having 5 to 25        aromatic ring atoms, which may be substituted by one or more        radicals R¹; two substituents R which are bonded to the same        carbon atom or to adjacent carbon atoms may optionally form a        monocyclic or polycyclic, aliphatic, aromatic or heteroaromatic        ring system here, which may be substituted by one or more        radicals R¹;    -   R¹ is defined as above.

Particular preference is given to compounds of the above-mentionedformulae (1), (2), (1a), (1b), (2a) and (2b), for which:

-   -   X is N;    -   Y¹, Y² stand, identically or differently on each occurrence, for        O or NR, where the radical R bonded to the nitrogen is not equal        to H; preferably: Y¹ stands for O and Y² stands for NR, or Y¹        stands for NR and Y² stands for O, or Y¹ and Y² stand for NR;    -   Y³ stands for NR, where the radical R bonded to the nitrogen is        not equal to H, or CR₂;    -   L stands for a single bond;    -   Ar stands, identically or differently on each occurrence, for an        aromatic or heteroaromatic ring system having 6 to 18 aromatic        ring atoms, preferably having 6 to 13 aromatic ring atoms, which        may in each case be substituted by one or more radicals R, but        is preferably unsubstituted;    -   n in formulae (1a) to (2b) is on each occurrence, identically or        differently, 0 or 1;    -   m in formulae (1a) to (2b) is 0;    -   in formulae (1a) to (2b) is 0;    -   R is selected, identically or differently on each occurrence,        from the group consisting of H, D, F, CN, N(Ar¹)₂, a        straight-chain alkyl group having 1 to 8 C atoms, preferably        having 1, 2, 3 or 4 C atoms, or a branched or cyclic alkyl group        having 3 to 8 C atoms, preferably having 3 or 4 C atoms, or an        alkenyl group having 2 to 8 C atoms, preferably having 2, 3 or 4        C atoms, each of which may be substituted by one or more        radicals R¹, but is preferably unsubstituted, or an aromatic or        heteroaromatic ring system having 6 to 24 aromatic ring atoms,        preferably having 6 to 18 aromatic ring atoms, particularly        preferably having 6 to 12 aromatic ring atoms, which may in each        case be substituted by one or more non-aromatic radicals R¹, but        is preferably unsubstituted; two substituents R which are bonded        to the same carbon atom or to adjacent carbon atoms may        optionally form a monocyclic or polycyclic, aliphatic ring        system here, which may be substituted by one or more radicals        R¹, but is preferably unsubstituted;    -   R¹ is defined as above.

The groups containing Y¹ and Y² are dibenzofuran derivatives for Y¹ orY² ═O, carbazole derivatives for Y¹ or Y²═NR, dibenzothiophenederivatives for Y¹ or Y²═S and fluorene derivatives for Y¹ or Y²═C(R)₂.If the two radicals R in the CR₂ group form a ring with one another, aspiro system forms therefrom, for example a spirobifluorene derivativeif the radicals R stand for phenyl.

These groups may be linked to one another in various positions and maybe substituted in various positions. The numbering of the positions ofthe individual groups is depicted diagrammatically below by the formulae(4) and (5), where the compounds according to the invention arisethrough linking of the formulae (4) and (5) to one another via a groupL:

For compounds of the formula (1), the links 1-1′, 1-2′, 1-3′, 1-4′,2-1′, 2-2′, 2-3′, 2-4′, 3-1′, 3-2′, 3-3′, 3-4′, 4-1′, 4-2′, 4-3′ and4-4′ are thus suitable. A link 1-2′ here, for example, means that thegroup of the formula (4) and the group of the formula (5) are linked toone another via a group L via the 1-position and 2′-positionrespectively.

For compounds of the formula (2), the links 6-1′, 6-2′, 6-3′, 6-4′,7-1′, 7-2′, 7-3′, 7-4′, 8-1′, 8-2′, 8-3′ and 8-4′ are suitable.

In principle, all linking patterns indicated above can be combined withthe preferences indicated above for the symbols and indices. Thepreferred linking pattern depends on the choice of Y¹ and Y².

If Y¹ stands for O, NR or S, the group of the formula (4) is preferablylinked via the 1-position, the 2-position or the 3-position in formula(1) or via the 8-position in formula (2). The links 1-1′, 1-2′, 1-3′,1-4′, 2-1′, 2-2′, 2-3′, 2-4′, 3-1′, 3-2′, 3-3′ and 3-4′ are thuspreferred for compounds of the formula (1) where Y¹=0, NR or S and thelinks 8-1′, 8-2′, 8-3′ and 8-4′ are thus preferred for compounds of theformula (2).

Preferred embodiments of the compounds according to the invention arethus the compounds of the following formulae (6), (7), (8) and (9)

where Y¹ stands for O, NR or S, the other symbols used have the meaningsgiven above and A preferably stands, identically or differently, for CRand W preferably stands, identically or differently on each occurrence,for CR or two groups W stand for a group of the formula (3) indicatedabove and the other groups W stand for CR. Particularly preferably, Aand W stand, identically or differently on each occurrence, for CR.

If Y¹ stands for C(R)₂, the group of the formula (4) is preferablylinked via the 2-position in formula (1) or via the 7-position informula (2). The links 2-1′, 2-2′, 2-3′ and 2-4′ are thus preferred forcompounds of the formula (1) where Y¹═C(R)₂ and the links 7-1′, 7-2′,7-3′ and 7-4′ are thus preferred for compounds of the formula (2). ForY═C(R)₂, a compound of the formula (1) and not a compound of the formula(2), in particular, is involved. A preferred embodiment of the compoundsaccording to the invention for Y¹ ═CR₂ is thus the compound of thefollowing formula (10),

where the symbols used have the meanings given above and where A and Wpreferably stand, identically or differently on each occurrence, for CR.

If Y² stands for O, the group of the formula (5) is preferably linkedvia the 1′-, 3′- or 4′-position. The links 1-1′, 1-3′, 1-4′, 2-1′, 2-3′,2-4′, 3-1′, 3-3′, 3-4′, 4-1′, 4-3′ and 4-4′ are thus preferred forcompounds of the formula (1). The links 6-1′, 6-3′, 6-4′, 7-1′, 7-3′,7-4′, 8-1′, 8-3′ and 8-4′ are preferred for compounds of the formula(2).

If Y² stands for NR, the group of the formula (5) is preferably linkedvia the 2′- or 3′-position. The links 1-2′, 1-3′, 2-2′, 2-3′, 3-2′,3-3′, 4-2′ and 4-3′ are thus preferred for compounds of the formula (1).The links 6-2′, 6-3′, 7-2′, 7-3′, 8-2′ and 8-3′ are preferred forcompounds of the formula (2).

If Y² stands for S, the group of the formula (5) is preferably linkedvia the 1-, 2-, 3- or 4-position. The links 1-1′, 1-2′, 1-3′, 1-4′,2-1′, 2-2′, 2-3′, 2-4′, 3-1′, 3-2′, 3-3′, 3-4′, 4-1′, 4-2′, 4-3′ and4-4′ are thus preferred for compounds of the formula (1). The links6-1′, 6-2′, 6-3′, 6-4′, 7-1′, 7-2′, 7-3′, 7-4′, 8-1′, 8-2′, 8-3′ and8-4′ are preferred for compounds of the formula (2).

If Y² stands for C(R)₂, the group of the formula (5) is preferablylinked via the 1′-, 2′- or 4′-position, particularly preferably via the2′- or 4′-position.

The links 1-1′, 2-1′, 3-1′, 4-1′, 1-2′, 2-2′, 3-2′, 4-2′, 1-4′, 2-4′,3-4′ and 4-4′ are thus preferred for compounds of the formula (1) andthe links 6-1′, 7-1′, 8-1′, 6-2′, 7-2′, 8-2′, 6-4′, 7-4′ and 8-4′ arethus preferred for compounds of the formula (2).

The precise preferred linking pattern for the groups Y² indicated abovein each case depends on the group Y¹ used, as described above.

Preference is given to compounds of the formula (8) indicated above inwhich Y² stands for NR, O or S and the group of the formula (5) islinked via the 3′-position, in accordance with the following formula(8a) and preferably in accordance with the following formula (8b),

where Y¹ stands for O, NR or S, Y² stands for NR, O or S and the othersymbols and indices used have the meanings given above and in particularthe meanings given as preferred and particularly preferred above.

Particular preference is thus given to the compounds of the followingformula (8c),

where the following applies to the symbols and indices used:

-   -   Y¹, Y² stand, identically or differently on each occurrence, for        O, NR, where the radical R bonded to the nitrogen is not equal        to H, or S, with the proviso that at least one of the groups Y¹        and/or Y² stands for NR, and preferably stand for O or NR, where        the radical R bonded to the nitrogen is not equal to H;    -   Ar stands, identically or differently on each occurrence, for an        aromatic or heteroaromatic ring system having 6 to 24 aromatic        ring atoms, preferably having 6 to 18 aromatic ring atoms, which        may in each case be substituted by one or more radicals R, but        is preferably unsubstituted;    -   n is, identically or differently on each occurrence, 0, 1, 2 or        3, preferably 0, 1 or 2, particularly preferably 0 or 1;    -   m is, identically or differently on each occurrence, 0, 1 or 2,        preferably 0 or 1, particularly preferably 0;    -   is 0 or 1, particularly preferably 0;    -   R is selected, identically or differently on each occurrence,        from the group consisting of H, D, F, CN, N(Ar¹)₂, C(═O)Ar¹,        P(═O)(Ar¹)₂, a straight-chain alkyl or alkoxy group having 1 to        10 C atoms or a branched or cyclic alkyl or alkoxy group having        3 to 10 C atoms or an alkenyl group having 2 to 10 C atoms, each        of which may be substituted by one or more radicals R¹, where        one or more non-adjacent CH₂ groups may be replaced by O and        where one or more H atoms may be replaced by D or F, an aromatic        or heteroaromatic ring system having 5 to 24 aromatic ring        atoms, which may in each case be substituted by one or more        radicals R¹, or an aralkyl or heteroaralkyl group having 5 to 25        aromatic ring atoms, which may be substituted by one or more        radicals R¹; two substituents R which are bonded to the same        carbon atom or to adjacent carbon atoms may optionally form a        monocyclic or polycyclic, aliphatic, aromatic or heteroaromatic        ring system here, which may be substituted by one or more        radicals R¹; R is preferably selected, identically or        differently on each occurrence, from the group consisting of H,        D, F, CN, N(Ar¹)₂, a straight-chain alkyl group having 1 to 8 C        atoms, preferably having 1, 2, 3 or 4 C atoms, or a branched or        cyclic alkyl group having 3 to 8 C atoms, preferably having 3 or        4 C atoms, or an alkenyl group having 2 to 8 C atoms, preferably        having 2, 3 or 4 C atoms, each of which may be substituted by        one or more radicals R¹, but is preferably unsubstituted, or an        aromatic or heteroaromatic ring system having 6 to 24 aromatic        ring atoms, preferably having 6 to 18 aromatic ring atoms,        particularly preferably having 6 to 12 aromatic ring atoms,        which may in each case be substituted by one or more        non-aromatic radicals R¹, but is preferably unsubstituted; two        substituents R which are bonded to the same carbon atom or to        adjacent carbon atoms may optionally form a monocyclic or        polycyclic, aliphatic ring system here, which may be substituted        by one or more radicals R¹, but is preferably unsubstituted.

R¹ here has the meanings given above and, if Y¹ and/or Y² stand(s) forNR, this radical R is preferably selected from the substituents asindicated above as preferred substituents on R.

Very particular preference is given to a compound of the followingformula (8d),

where the symbols and indices used have the meanings given under formula(8c) and the radical R bonded to the nitrogen stands for an aromatic orheteroaromatic ring system having 5 to 24 aromatic ring atoms, which mayin each case be substituted by one or more radicals R¹, preferably foran aromatic or heteroaromatic ring system having 6 to 18 aromatic ringatoms, which may be substituted by one or more radicals R¹.

Examples of suitable compounds according to the invention are thestructures shown below.

The compounds according to the invention can be prepared by synthesissteps known to the person skilled in the art, such as, for example,bromination, Suzuki coupling, Ullmann coupling, Hartwig-Buchwaldcoupling, etc. A suitable synthetic process is depicted in general termsin Scheme 1 below.

Processing of the compounds according to the invention from the liquidphase, for example by spin coating or by printing processes, requiresformulations of the compounds according to the invention. Theseformulations can be, for example, solutions, dispersions or emulsions.It may be preferred to use mixtures of two or more solvents for thispurpose. Suitable and preferred solvents are, for example, toluene,anisole, o-, m- or p-xylene, methyl benzoate, mesitylene, tetralin,veratrol, THF, methyl-THF, THP, chlorobenzene, dioxane, phenoxytoluene,in particular 3-phenoxytoluene, (-)-fenchone,1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene,1-methylnaphthalene, 2-methylbenzothiazole, 2-phenoxyethanol,2-pyrrolidinone, 3-methylanisole, 4-methylanisole, 3,4-dimethylanisole,3,5-dimethylanisole, acetophenone, -terpineol, benzothiazole, butylbenzoate, cumene, cyclohexanol, cyclohexanone, cyclohexylbenzene,decalin, dodecylbenzene, ethyl benzoate, indane, methyl benzoate, NMP,p-cymene, phenetole, 1,4-diisopropylbenzene, dibenzyl ether, diethyleneglycol butyl methyl ether, triethylene glycol butyl methyl ether,diethylene glycol dibutyl ether, triethylene glycol dimethyl ether,diethylene glycol mono-butyl ether, tripropylene glycol dimethyl ether,tetraethylene glycol dimethyl ether, 2-isopropylnaphthalene,pentylbenzene, hexylbenzene, heptyl-benzene, octylbenzene,1,1-bis(3,4-dimethylphenyl)ethane, hexamethyl-indane or mixtures ofthese solvents.

The present invention therefore furthermore relates to a formulationcomprising a compound according to the invention and at least onefurther compound. The further compound may be, for example, a solvent,in particular one of the above-mentioned solvents or a mixture of thesesolvents. However, the further compound may also be at least one furtherorganic or inorganic compound which is likewise employed in theelectronic device, for example an emitting compound, in particular aphosphorescent dopant, and/or a further matrix material. Suitableemitting compounds and further matrix materials are indicated below inconnection with the organic electroluminescent device. This furthercompound may also be polymeric.

The compounds and mixtures according to the invention are suitable foruse in an electronic device. An electronic device here is taken to meana device which comprises at least one layer which comprises at least oneorganic compound. However, the component here may also compriseinorganic materials or also layers built up entirely from inorganicmaterials.

The present invention therefore furthermore relates to the use of thecompounds or mixtures according to the invention in an electronicdevice, in particular in an organic electroluminescent device.

The present invention again furthermore relates to an electronic devicecomprising at least one of the compounds or mixtures according to theinvention mentioned above. The preferences stated above for the compoundalso apply to the electronic devices.

The electronic device is preferably selected from the group consistingof organic electroluminescent devices (OLEDs, PLEDs), organic integratedcircuits (O-ICs), organic field-effect transistors (O-FETs), organicthin-film transistors (O-TFTs), organic light-emitting transistors(O-LETs), organic solar cells (O-SCs), organic dye-sensitised solarcells, organic optical detectors, organic photoreceptors, organicfield-quench devices (O-FQDs), light-emitting electrochemical cells(LECs), organic laser diodes (0-lasers) and “organic plasmon emittingdevices” (D. M. Koller et al., Nature Photonics 2008, 1-4), preferablyorganic electroluminescent devices (OLEDs, PLEDs), in particularphosphorescent OLEDs.

The organic electroluminescent device comprises a cathode, an anode andat least one emitting layer. Apart from these layers, it may alsocomprise further layers, for example in each case one or morehole-injection layers, hole-transport layers, hole-blocking layers,electron-transport layers, electron-injection layers, exciton-blockinglayers, electron-blocking layers and/or charge-generation layers. It islikewise possible for interlayers, which have, for example, anexciton-blocking function, to be introduced between two emitting layers.However, it should be pointed out that each of these layers does notnecessarily have to be present. The organic electroluminescent devicehere may comprise one emitting layer or a plurality of emitting layers.If a plurality of emission layers are present, these preferably have intotal a plurality of emission maxima between 380 nm and 750 nm,resulting overall in white emission, i.e. various emitting compoundswhich are able to fluoresce or phosphoresce are used in the emittinglayers. Particular preference is given to systems having three emittinglayers, where the three layers exhibit blue, green and orange or redemission (for the basic structure see, for example, WO 2005/011013).These can be fluorescent or phosphorescent emission layers or hybridsystems, in which fluorescent and phosphorescent emission layers arecombined with one another. A white-emitting electroluminescent devicecan be used, for example, for lighting applications, but also incombination with a coloured filter for full-colour displays.

The compound according to the invention in accordance with theembodiments indicated above can be employed in various layers, dependingon the precise structure. Preference is given to an organicelectroluminescent device comprising a compound of the formula (1) orformula (2) or in accordance with the preferred embodiments as matrixmaterial for fluorescent or phosphorescent emitters, in particular forphosphorescent emitters, and/or in an electron-transport layer and/or inan electron-blocking or exciton-blocking layer and/or in ahole-transport layer, depending on the precise substitution. Thepreferred embodiments indicated above also apply to the use of thematerials in organic electronic devices.

In a preferred embodiment of the invention, the compound of the formula(1) or formula (2) or in accordance with the preferred embodiments isemployed as matrix material for a fluorescent or phosphorescentcompound, in particular for a phosphorescent compound, in an emittinglayer. The organic electroluminescent device here may comprise oneemitting layer or a plurality of emitting layers, where at least oneemitting layer comprises at least one compound according to theinvention as matrix material.

If the compound of the formula (1) or formula (2) or in accordance withthe preferred embodiments is employed as matrix material for an emittingcompound in an emitting layer, it is preferably employed in combinationwith one or more phosphorescent materials (triplet emitters).Phosphorescence in the sense of this invention is taken to mean theluminescence from an excited state having spin multiplicity >1, inparticular from an excited triplet state. For the purposes of thisapplication, all luminescent transition-metal complexes and luminescentlanthanide complexes, in particular all iridium, platinum and coppercomplexes, are to be regarded as phosphorescent compounds.

The mixture comprising the compound of the formula (1) or formula (2) orin accordance with the preferred embodiments and the emitting compoundcomprises between 99 and 1% by vol., preferably between 98 and 10% byvol., particularly preferably between 97 and 60% by vol., in particularbetween 95 and 80% by vol., of the compound of the formula (1) or inaccordance with the preferred embodiments, based on the entire mixturecomprising emitter and matrix material. Correspondingly, the mixturecomprises between 1 and 99% by vol., preferably between 2 and 90% byvol., particularly preferably between 3 and 40% by vol., in particularbetween 5 and 20% by vol., of the emitter, based on the entire mixturecomprising emitter and matrix material. If the compounds are processedfrom solution, the corresponding amounts in % by weight are preferablyused instead of the amounts indicated above in % by vol.

Suitable phosphorescent compounds (=triplet emitters) are, inparticular, compounds which emit light, preferably in the visibleregion, on suitable excitation and in addition contain at least one atomhaving an atomic number greater than 20, preferably greater than 38 andless than 84, particularly preferably greater than 56 and less than 80,in particular a metal having this atomic number. The phosphorescentemitters used are preferably compounds which contain copper, molybdenum,tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium,platinum, silver, gold or europium, in particular compounds whichcontain iridium or platinum. For the purposes of the present invention,all luminescent compounds which contain the above-mentioned metals areregarded as phosphorescent compounds.

Examples of the emitters described above are revealed by theapplications WO 00/70655, WO 2001/41512, WO 2002/02714, WO 2002/15645,EP 1191613, EP 1191612, EP 1191614, WO 05/033244, WO 05/019373, US2005/0258742, WO 2009/146770, WO 2010/015307, WO 2010/031485, WO2010/054731, WO 2010/054728, WO 2010/086089, WO 2010/099852, WO2010/102709, WO 2011/032626, WO 2011/066898, WO 2011/157339, WO2012/007086, WO 2014/008982, WO 2014/023377, WO 2014/094961, WO2014/094960 and the as yet unpublished applications EP 13004411.8, EP14000345.0, EP 14000417.7 and EP 14002623.8. In general, allphosphorescent complexes as used in accordance with the prior art forphosphorescent OLEDs and as are known to the person skilled in the artin the area of organic electroluminescence are suitable, and the personskilled in the art will be able to use further phosphorescent complexeswithout inventive step.

A further preferred embodiment of the present invention is the use ofthe compound of the formula (1) or formula (2) or the above-mentionedpreferred embodiments as matrix material for a phosphorescent emitter incombination with a further matrix material. In a preferred embodiment ofthe invention, the further matrix material is a hole-transportingcompound. In a further preferred embodiment of the invention, thefurther matrix material is an electron-transporting compound. In still afurther preferred embodiment, the further matrix material is a compoundhaving a large band gap which is not or not to a significant extentinvolved in the hole and electron transport in the layer.

Suitable matrix materials which can be employed in combination with thecompounds of the formula (1) or formula (2) or in accordance with thepreferred embodiments are aromatic ketones, aromatic phosphine oxides oraromatic sulfoxides or sulfones, for example in accordance with WO2004/013080, WO 2004/093207, WO 2006/005627 or WO 2010/006680,triarylamines, in particular monoamines, for example in accordance withWO 2014/015935, carbazole derivatives, for example CBP(N,N-biscarbazolylbiphenyl) or the carbazole derivatives disclosed in WO2005/039246, US 2005/0069729, JP 2004/288381, EP 1205527 or WO2008/086851, indolocarbazole derivatives, for example in accordance withWO 2007/063754 or WO 2008/056746, indenocarbazole derivatives, forexample in accordance with WO 2010/136109 or WO 2011/000455,azacarbazole derivatives, for example in accordance with EP 1617710, EP1617711, EP 1731584, JP 2005/347160, bipolar matrix materials, forexample in accordance with WO 2007/137725, silanes, for example inaccordance with WO 005/111172, azaboroles or boronic esters, for examplein accordance with WO 2006/117052, triazine derivatives, for example inaccordance with WO 2010/015306, WO 2007/063754 or WO 2008/056746, zinccomplexes, for example in accordance with EP 652273 or WO 2009/062578,diazasilole or tetraazasilole derivatives, for example in accordancewith WO 2010/054729, diazaphosphole derivatives, for example inaccordance with WO 2010/054730, bridged carbazole derivatives, forexample in accordance with US 2009/0136779, WO 2010/050778, WO2011/042107, WO 2011/088877 or WO 2012/143080, triphenylene derivatives,for example in accordance with WO 2012/048781, lactams, for example inaccordance with WO 2011/116865, WO 2011/137951 or WO 2013/064206, or4-spirocarbazole derivatives, for example in accordance with WO2014/094963 or the as yet unpublished application EP 14002104.9. Afurther phosphorescent emitter which emits at shorter wavelength thanthe actual emitter may likewise be present in the mixture as co-host.

Preferred co-host materials are triarylamine derivatives, in particularmonoamines, indenocarbazole derivatives, 4-spirocarbazole derivatives,lactams and carbazole derivatives.

Preferred triarylamine derivatives which are employed as co-hostmaterials together with the compounds according to the invention areselected from the compounds of the following formula (11),

where Ar has, identically or differently on each occurrence, themeanings given above. The groups Ar are preferably selected, identicallyor differently on each occurrence, from groups Ar-1 to Ar-19 indicatedabove.

In a preferred embodiment of the compounds of the formula (11), at leastone group Ar is selected from a biphenyl group, which can be an ortho-,meta- or para-biphenyl group. In a further preferred embodiment of thecompounds of the formula (11), at least one group Ar is selected from afluorene group or spirobifluorene group, where these groups may each bebonded to the nitrogen atom in the 1-, 2-, 3- or 4-position. In still afurther preferred embodiment of the compounds of the formula (11), atleast one group Ar is selected from a phenylene or biphenyl group, whichis an ortho-, meta- or para-linked group which is substituted by adibenzofuran group, a dibenzothiophene group or a carbazole group, inparticular a dibenzofuran group, where the dibenzofuran ordibenzothiophene group is linked to the phenylene or biphenyl group viathe 1-, 2-, 3- or 4-position and where the carbazole group is linked tothe phenylene or biphenyl group via the 1-, 2-, 3- or 4-position or viathe nitrogen atom.

In a particularly preferred embodiment of the compounds of the formula(11), one group Ar is selected from a fluorene or spirobifluorene group,in particular a 4-fluorene or 4-spirobifluorene group, and one group Aris selected from a biphenyl group, in particular a para-biphenyl group,or a fluorene group, in particular a 2-fluorene group, and the thirdgroup Ar is selected from a para-phenylene group or a para-biphenylgroup, which is substituted by a dibenzofuran group, in particular a4-dibenzofuran group, or a carbazole group, in particular an N-carbazolegroup or a 3-carbazole group.

Preferred indenocarbazole derivatives which are employed as co-hostmaterials together with the compounds according to the invention areselected from the compounds of the following formula (12),

where Ar and R have the meanings given above. Preferred embodiments ofthe group Ar here are structures Ar-1 to Ar-19 indicated above.

A preferred embodiment of the compounds of the formula (12) are thecompounds of the following formula (12a),

where Ar and R have the meanings given above. The two groups R which arebonded to the indeno carbon atom preferably stand, identically ordifferently, for an alkyl group having 1 to 4 C atoms, in particular formethyl groups, or for an aromatic ring system having 6 to 12 C atoms, inparticular for phenyl groups. Particularly preferably, the two groups Rwhich are bonded to the indeno carbon atom stand for methyl groups.Furthermore preferably, the substituent R which is bonded to theindenocarbazole skeleton in formula (12a) stands for H or for acarbazole group, which can be bonded to the indenocarbazole skeleton viathe 1-, 2-, 3- or 4-position or via the N atom, in particular via the3-position.

Preferred 4-spirocarbazole derivatives which are employed as co-hostmaterials together with the compounds according to the invention areselected from the compounds of the following formula (13),

where Ar and R have the meanings given above. Preferred embodiments ofthe group Ar here are structures Ar-1 to Ar-19 indicated above.

A preferred embodiment of the compounds of the formula (13) are thecompounds of the following formula (13a),

where Ar and R have the meanings given above.

Preferred lactams which are employed as co-host materials together withthe compounds according to the invention are selected from the compoundsof the following formula (14),

where R has the meanings given above.

A preferred embodiment of the compounds of the formula (14) are thecompounds of the following formula (14a),

where R has the meanings given above. R here preferably stands,identically or differently on each occurrence, for H or an aromatic orheteroaromatic ring system having 5 to 40 aromatic ring atoms, which maybe substituted by one or more radicals R¹. The substituents R are veryparticularly preferably selected from the group consisting of H or anaromatic or heteroaromatic ring system having 6 to 18 aromatic ringatoms, preferably having 6 to 13 aromatic ring atoms, which may in eachcase be substituted by one or more non-aromatic radicals R¹, but ispreferably unsubstituted. Examples of suitable substituents R areselected from the group consisting of phenyl, ortho-, meta- orpara-biphenyl, terphenyl, in particular branched terphenyl,quaterphenyl, in particular branched quaterphenyl, 1-, 2-, 3- or4-fluorenyl, 1-, 2-, 3- or 4-spirobifluorenyl, pyridyl, pyrimidinyl, 1-,2-, 3- or 4-dibenzofuranyl, 1-, 2-, 3- or 4-dibenzothienyl and 1-, 2-,3- or 4-carbazolyl, each of which may be substituted by one or moreradicals R¹, but is preferably unsubstituted. Suitable structures R hereare the same structures as depicted above for Ar-1 to Ar-19, where thesestructures are substituted by R¹ instead of R.

In a further embodiment of the invention, the organic electroluminescentdevice according to the invention does not comprise a separatehole-injection layer and/or hole-transport layer and/or hole-blockinglayer and/or electron-transport layer, i.e. the emitting layer isdirectly adjacent to the hole-injection layer or the anode, and/or theemitting layer is directly adjacent to the electron-transport layer orthe electron-injection layer or the cathode, as described, for example,in WO 2005/053051. It is furthermore possible to use a metal complexwhich is identical or similar to the metal complex in the emitting layeras hole-transport or hole-injection material directly adjacent to theemitting layer, as described, for example, in WO 2009/030981.

It is furthermore possible to employ the compounds according to theinvention in a hole-blocking or electron-transport layer. This applies,in particular, to compounds according to the invention which do notcontain a carbazole structure. These may preferably also be substitutedby one or more further electron-transporting groups, for examplebenzimidazole groups.

In the further layers of the organic electroluminescent device accordingto the invention, all materials as are usually employed in accordancewith the prior art can be used. The person skilled in the art willtherefore be able to employ, without inventive step, all materials knownfor organic electroluminescent devices in combination with the compoundsof the formula (1) or formula (2) according to the invention or inaccordance with the preferred embodiments.

Preference is furthermore given to an organic electroluminescent device,characterised in that one or more layers are applied by means of asublimation process, in which the materials are applied by vapourdeposition in vacuum sublimation units at an initial pressure of lessthan 10⁻⁵ mbar, preferably less than 10⁻⁶ mbar. However, it is alsopossible for the initial pressure to be even lower or higher, forexample less than 10⁻⁷ mbar.

Preference is likewise given to an organic electroluminescent device,characterised in that one or more layers are applied by means of theOVPD (organic vapour phase deposition) process or with the aid ofcarrier-gas sublimation, in which the materials are applied at apressure between 10⁻⁵ mbar and 1 bar. A special case of this process isthe OVJP (organic vapour jet printing) process, in which the materialsare applied directly through a nozzle and are thus structured (forexample M. S. Arnold et al., Appl. Phys. Lett. 2008, 92, 053301).

Preference is furthermore given to an organic electroluminescent device,characterised in that one or more layers are produced from solution,such as, for example, by spin coating, or by means of any desiredprinting process, such as, for example, ink-jet printing, LITI (lightinduced thermal imaging, thermal transfer printing), screen printing,flexographic printing, offset printing or nozzle printing. Solublecompounds, which are obtained, for example, by suitable substitution,are necessary for this purpose.

Also possible are hybrid processes, in which, for example, one or morelayers are applied from solution and one or more further layers areapplied by vapour deposition. Thus, for example, it is possible to applythe emitting layer from solution and to apply the electron-transportlayer by vapour deposition.

These processes are generally known to the person skilled in the art andcan be applied by him without inventive step to organicelectroluminescent devices comprising the compounds according to theinvention.

The compounds according to the invention generally have very goodproperties on use in organic electroluminescent devices. In particular,the lifetime on use of the compounds according to the invention inorganic electroluminescent devices is significantly better compared withsimilar compounds in accordance with the prior art. The other propertiesof the organic electroluminescent device, in particular the efficiencyand the voltage, are likewise better or at least comparable.

The invention is now explained in greater detail by the followingexamples, without wishing to restrict it thereby.

EXAMPLES

The following syntheses are carried out, unless indicated otherwise, indried solvents under a protective-gas atmosphere. The solvents andreagents can be purchased, for example, from Sigma-ALDRICH or ABCR. Thecorresponding CAS numbers are in each case also indicated for thecompounds that are known from the literature.

Synthesis Examples a) Triazine synthesis:2,4-Bisbiphenyl-3-yl-6-chloro-1,3,5-triazine

5.2 g of magnesium (0.215 mol) are initially introduced in a 500 mlfour-necked flask, and a solution of 50 g of bromobiphenyl (214 mmol) in200 ml of THF is slowly added dropwise. The reaction mixture is heatedat the boil for 1.5 h and subsequently cooled to room temperature.Cyanogen chloride (17.2 g, 93 mmol) in 150 ml of THF is initiallyintroduced in a second flask and cooled to 0° C. The cooled Grignardreagent is added dropwise at this temperature, and the mixture isstirred at room temperature for 12 h. After this time, 150 ml of HCl areadded to the reaction mixture, and the aqueous phase is extracted threetimes with dichloromethane. The combined organic phases are washed withwater, dried over Na₂SO₄ and evaporated. The residue is recrystallisedfrom EtOH. The yield is 32.8 g (78 mmol, 84%).

b) 4-Bromo-9-methyl-9-phenyl-9H-fluorene

30 g (94 mmol) of 2,2′-dibromobiphenyl are dissolved in 200 ml of driedTHF in a flask which has been dried by heating. The reaction mixture iscooled to −78° C. At this temperature, 37.7 ml of a 2.5 M solution ofn-butyllithium in hexane (94 mmol) are slowly added dropwise (duration:about 1 h). The batch is stirred at −70° C. for a further 1 h. 11.1 mlof acetophenone (94 mmol) are subsequently dissolved in 100 ml of THFand added dropwise at −70° C. When the addition is complete, thereaction mixture is slowly warmed to room temperature, quenched withNH₄Cl and subsequently concentrated in a rotary evaporator. 300 ml ofacetic acid are carefully added to the concentrated solution, and 50 mlof fuming HCl are subsequently added. The batch is heated at 75° C. for6 h, during which a white solid precipitates out. The batch is cooled toroom temperature, and the solid which has precipitated out is filteredoff with suction and rinsed with methanol. The residue is dried at 40°C. in vacuo. The yield is 25.3 g (75 mmol) (80% of theory).

c) 4-Bromo-9,9-diphenyl-9H-fluorene

37 g (152 mmol) of 2,2′-dibromobiphenyl are dissolved in 300 ml of driedTHE in a flask which has been dried by heating. The reaction mixture iscooled to −78° C. At this temperature, 75 ml of a 15% solution ofn-butyllithium in hexane (119 mmol) are slowly added dropwise (duration:about 1 h). The batch is stirred at −70° C. for a further 1 h. 21.8 g ofbenzophenone (119 mmol) are subsequently dissolved in 100 ml of THF andadded dropwise at −70° C. When the addition is complete, the reactionmixture is slowly warmed to room temperature, quenched with NH₄Cl andsubsequently concentrated in a rotary evaporator. 510 ml of acetic acidare carefully added to the concentrated solution, and 100 ml of fumingHCl are subsequently added. The batch is heated at 75° C. for 4 h,during which a white solid precipitates out. The batch is then cooled toroom temperature, and the solid which has precipitated out is filteredoff with suction and rinsed with methanol. The residue is dried at 40°C. in vacuo. The yield is 33.2 g (83 mmol) (70% of theory).

The following brominated compounds are prepared analogously:

Starting Starting material 1 material 2 Product Yield c1

78% c2

70% c3

82%

d) 6-Bromo-2-fluoro-2′-methoxybiphenyl

200 g (664 mmol) of 1-bromo-3-fluoro-2-iodobenzene, 101 g (664 mmol) of2-methoxyphenylboronic acid and 137.5 g (997 mmol) of sodium tetraborateare dissolved in 1000 ml of THF and 600 ml of water and degassed. 9.3 g(13.3 mmol) of bis(triphenylphosphine)palladium(II) chloride and 1 g (20mmol) of hydrazinium hydroxide are added. The reaction mixture issubsequently stirred at 70° C. under a protective-gas atmosphere for 48h. The cooled solution is extended with toluene, washed a number oftimes with water, dried and evaporated. The product is purified bycolumn chromatography on silica gel with toluene/heptane (1:2). Yield:155 g (553 mmol), 83% of theory.

The following compounds are prepared analogously:

Starting Starting material 1 material 2 Product Yield d1

77% d2

74% d3

76% d4

71%

e) 6′-Bromo-2′-fluorobiphenyl-2-ol

112 g (418 mmol) of 6-bromo-2-fluoro-2′-methoxybiphenyl are dissolved in2 I of dichloromethane and cooled to 5° C. 41.01 ml (431 mmol) of borontribromide are added dropwise to this solution over the course of 90min., and stirring is continued overnight. Water is subsequently slowlyadded to the mixture, and the organic phase is washed three times withwater, dried over Na₂SO₄, evaporated in a rotary evaporator and purifiedby chromatography. Yield: 104 g (397 mmol), 98% of theory.

The following compounds are prepared analogously:

Starting material 1 Product Yield e1

92% e2

90% e3

93% e4

94%

f) 1-Bromodibenzofuran

111 g (416 mmol) of 6′-bromo-2′-fluorobiphenyl-2-ol are dissolved in 2 Iof SeccoSolv® DMF (max. 0.003% of H₂O) and cooled to 5° C. 20 g (449mmol) of sodium hydride (60% suspension in paraffin oil) are added tothis solution in portions, and the mixture is stirred for a further 20min. after the addition is complete and then heated at 100° C. for 45min. After cooling, 500 ml of ethanol are slowly added to the mixture,which is then evaporated in a rotary evaporator and then purified bychromatography. Yield: 90 g (367 mmol), 88.5% of theory.

The following compounds are prepared analogously:

Starting material 1 Product Yield f1

81% f2

78% f3

73% f4

79%

g) Dibenzofuran-1-boronic acid and boronic acid esters

180 g (728 mmol) of 1-bromodibenzofuran are dissolved in 1500 ml of dryTHF and cooled to −78° C. At this temperature, 305 ml (764 mmol/2.5 M inhexane) of n-butyllithium are added over the course of about 5 min., andthe mixture is subsequently stirred at −78° C. for a further 2.5 h. Atthis temperature, 151 g (1456 mmol) of trimethyl borate are added asrapidly as possible, and the reaction is allowed to come slowly to roomtemperature (about 18 h). The reaction solution is washed with water,the solid which has precipitated out is filtered off and the organicphase are dried azeotropically with toluene. The crude product is washedby stirring with toluene/methylene chloride at about 40° C. and filteredoff with suction. Yield: 146 g (690 mmol), 95% of theory.

The following compounds are prepared analogously:

Starting material 1 Product Yield g1 

81% g2 

78% g3 

73% g4 

79% g5 

73% g6 

70% g7 

70% g8 

78% g9 

81% g10

86% g11

83% g12

85% g13

82% g14

80% g15

83% g16

82% g17

81% g18

84%

g19) Synthesis of1-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-dibenzofuran

101 g (410 mmol) of 1-bromodibenzofuran are dissolved in 1500 ml of dryDMF together with 273 g (1055 mmol) of bis(pinacolato)diborane (CAS73183-34-3) under protective gas in a 500 ml flask and degassed for 30minutes. 121 g (1229 mmol) of potassium acetate and 8.4 g (37 mmol) ofpalladium acetate are subsequently added, and the batch is heatedovernight at 80° C. When the reaction is complete, the mixture isdiluted with 300 ml of toluene and extracted with water. The solvent isremoved in a rotary evaporator, and the product is recrystallised fromheptane. Yield: 118 g (401 mmol), 98% of theory.

h) 2-Dibenzofuran-1-yl-4,6-diphenyl-1,3,5-triazine

23 g (110.0 mmol) of dibenzofuran-1-boronic acid, 29.5 g (110.0 mmol) of2-chloro-4,6-diphenyl-1,3,5-triazine and 21 g (210.0 mmol) of sodiumcarbonate are suspended in 500 ml of ethylene glycol diamine ether and500 ml of water. 913 mg (3.0 mmol) of tri-o-tolylphosphine and then 112mg (0.5 mmol) of palladium(II) acetate are added to this suspension, andthe reaction mixture is heated under reflux for 16 h. After cooling, theorganic phase is separated off, filtered through silica gel, washedthree times with 200 ml of water and subsequently evaporated to dryness.The residue is recrystallised from toluene and fromdichloromethane/heptane. The yield is 37 g (94 mmol), corresponding to87% of theory.

The following compounds are prepared analogously:

Starting Starting material 1 material 2 Product Yield h1 

73% h2 

82% h3 

73% h4 

72% h5 

65% h6 

63% h7 

72% h8 

75% h9 

79% h10

81% h11

85% h12

80% h13

79% h14

77% h15

76% h16

71% h17

75% h18

76% h19

80% h20

79% h21

82%

i) 2-(8-Bromodibenzofuran-1-yl)-4,6-diphenyl-1,3,5-triazine

70 g (190.0 mmol) of 2-dibenzofuran-1-yl-4,6-diphenyl-1,3,5-triazine aresuspended in 2000 ml of acetic acid (100%) and 2000 ml of sulfuric acid(95-98%). 34 g (190 mmol) of NBS are added to this suspension inportions, and the mixture is stirred in the dark for 2 h. Water/ice arethen added, and the solid is separated off and rinsed with ethanol. Theresidue is recrystallised from toluene. The yield is 80 g (167 mmol),corresponding to 87% of theory.

The following compounds are prepared analogously:

Starting material 1 Product Yield i1 

80% i2 

41% i3 

52% i4 

64% i5 

33% i6 

73% i7 

78% i8 

80% i9 

70% i10

86% i11

88% i12

41% i13

73%

In the case of the dibenzothiophene derivatives, nitrobenzene isemployed instead of sulfuric acid and elemental bromine is employedinstead of NBS:

i14

55% i15

52%

j)3-[9-(4,6-Diphenyl-1,3,5-triazin-2-yl)dibenzofuran-2-yl]-9-phenyl-9H-carbazole

75 g (156 mmol) of2-(8-bromodibenzofuran-1-yl)-4,6-diphenyl-1,3,5-triazine, 50 g (172mmol) of N-phenylcarbazole-3-boronic acid and 36 g (340 mmol) of sodiumcarbonate are suspended in 1000 ml of ethylene glycol diamine ether and280 ml of water. 1.8 g (1.5 mmol) oftetrakis-(triphenylphosphine)palladium(0) are added to this suspension,and the reaction mixture is heated under reflux for 16 h. After cooling,the organic phase is separated off, filtered through silica gel, washedthree times with 200 ml of water and subsequently evaporated to dryness.The product is purified by column chromatography on silica gel withtoluene/heptane (1:2) and finally sublimed in a high vacuum (p=5×10⁻⁷mbar) (purity 99.9%). The yield is 50 g (78 mmol), corresponding to 50%of theory.

The following compounds are prepared analogously:

Starting material 1 Starting material 2 Product Yield j1

61% j2

67% j3

65% j4

53% j5

58% j6

54% j7

65% j8

71% j9

56% j10

79% j11

70% j12

82% j13

69% j14

65% j15

77% j16

82% j17

54% j18

67% j19

65% j20

63% j21

79% j22

65% j23

55% j24

67% j25

73% j26

66% j27

59% j28

64% j29

71% j30

62%

The following compounds are prepared analogously using 0.5 equivalent ofthe corresponding bromide:

j31 cmpn.

72% j32 cmpn.

73% j33

74% j34

77%

k) 3(1-Bromodibenzothiophen-3-yl)-9-phenyl-9H-carbazole

22 g (66 mmol) of 1,3-dibromodibenzothiophene, 17 g (664 mmol) ofN-phenylcarbazole-3-boronic acid and 13.7 g (100 mmol) of sodiumtetraborate are dissolved in 100 ml of THF and 60 ml of water anddegassed. 0.9 g (1.3 mmol) of bis(triphenylphosphine)palladium(II)chloride and 1 g (20 mmol) of hydrazinium hydroxide are added. Thereaction mixture is subsequently stirred at 70° C. under aprotective-gas atmosphere for 48 h. The cooled solution is extended withtoluene, washed a number of times with water, dried and evaporated. Theproduct is purified by column chromatography on silica gel withtoluene/heptane (1:2). Yield: 13.2 g (26 mmol), 40% of theory.

The following compounds are prepared analogously:

Starting material 1 Starting material 2 Product Yield k1

27% k2

29% k3

34% k4

24% k5

31%

l) 1-Bromo-8-iododibenzofuran

20 g (80 mmol) of dibenzofuran-1-boronic acid, 2.06 g (40.1 mmol) ofiodine, 3.13 g (17.8 mmol) of iodic acid, 80 ml of acetic acid, 5 ml ofsulfuric acid, 5 ml of water and 2 ml of chloroform are stirred at 65°C. for 3 h. After cooling, water is added to the mixture, and the solidwhich has precipitated out is filtered off with suction and washed threetimes with water. The residue is recrystallised from toluene and fromdichloromethane/heptane. The yield is 25.6 g (68 mmol), corresponding to85% of theory.

The following compounds are prepared analogously:

Starting material 1 Product Yieid l1

81% l2

84% l3

78%

m) 3-(9-Bromodibenzofuran-2-yl)-9-phenyl-9H-carbazole

58 g (156 mmol) of 1-bromo-8-iododibenzofuran, 50 g (172 mmol) ofN-phenylcarbazole-3-boronic acid and 36 g (340 mmol) of sodium carbonateare suspended in 1000 ml of ethylene glycol diamine ether and 280 ml ofwater. 1.8 g (1.5 mmol) of tetrakis(triphenylphosphine)palladium(0) areadded to this suspension, and the reaction mixture is heated underreflux for 16 h. After cooling, the organic phase is separated off,filtered through silica gel, washed three times with 200 ml of water andsubsequently evaporated to dryness. The yield is 48 g (89 mmol),corresponding to 64% of theory.

The following compounds are prepared analogously:

Starting Starting material 1 material 2 Product Yield m1

60% m2

62% m3

54% m4

50% m5

55% m6

56% m7

57% m8

61% m9

52% m10

50% m11

48% m12

52% m13

54% m14

57% m15

48% m16

46%

o) 8-(9-Phenyl-9H-carbazol-3-yl)dibenzofuran-1-boronic acid

20 g (182 mmol) of 3-(9-bromodibenzofuran-2-yl)-9-phenyl-9H-carbazoleare dissolved in 400 ml of dry THF and cooled to −78° C. At thistemperature, 77 ml (190 mmol/2.5 M in hexane) of n-butyllithium areadded over the course of about 5 min., and the mixture is subsequentlystirred at −78° C. for a further 2.5 h. At this temperature, 38 g (365mmol) of trimethyl borate are added as rapidly as possible, and thereaction is allowed to come slowly to room temperature (about 18 h). Thereaction solution is washed with water, the solid which has precipitatedout is filtered off and the organic phase are dried azeotropically withtoluene. The crude product is washed by stirring with toluene/methylenechloride at about 40° and filtered off with suction. Yield: 16.7 g (690mmol), 90% of theory.

The following compounds are prepared analogously:

Starting material Product Yield o1

81% o2

84% o3

82% o4

81% o5

79% o6

77% o7

75% o8

78% o9

76% o10

81% o11

80% o12

71% o13

69% o14

88% o15

78% o16

77%

p)3-{9-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]dibenzofuran-2-yl}-9-phenyl-9H-carbazole

49.8 g (110.0 mmol) of8-(9-phenyl-9H-carbazol-3-yl)dibenzofuran-1-boronic acid, 42.6 g (110.0mmol) of 2-(3-bromophenyl)-4,6-diphenyl-1,3,5-triazine and 26 g (210.0mmol) of sodium carbonate are suspended in 500 ml of ethylene glycoldimethyl ether and 500 ml of water. 913 mg (3.0 mmol) oftri-o-tolylphosphine and then 112 mg (0.5 mmol) of palladium(II) acetateare added to this suspension, and the reaction mixture is heated underreflux for 16 h. After cooling, the organic phase is separated off,filtered through silica gel, washed three times with 200 ml of water andsubsequently evaporated to dryness. The product is purified by columnchromatography on silica gel with toluene/heptane (1:2) and finallysublimed in a high vacuum (p=5×10⁻⁷ mbar) (purity 99.9%). The yield is52 g (72 mmol), corresponding to 78% of theory.

The following compounds are prepared analogously:

Starting material 1 Starting material 2 Product Yield p1

59% p2

67% p3

62% p4

69% p5

67% p6

68% p7

69% p8

60% p9

63% p10

66% p11

60% p12

61% p13

65% p14

63% p15

65% p16

63% p17

65% p18

67% p19

72% p20

66%

Production of the OLEDs

The data of various OLEDs are presented in the following Examples V1 toE37 (see Tables 1 and 2).

Pre-treatment for Examples V1-E37: Glass plates coated with structuredITO (indium tin oxide) in a thickness of 50 nm are coated with 20 nm ofPEDOT:PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate),purchased as CLEVIOS™ P VP Al 4083 from Heraeus Precious Metals GmbHGermany, applied by spin coating from aqueous solution) for improvedprocessing. These coated glass plates form the substrates to which theOLEDs are applied. The OLEDs have in principle the following layerstructure: substrate/hole-transport layer (HTL)/optional interlayer(IL)/electron-blocking layer (EBL)/emission layer (EML)/optionalhole-blocking layer (HBL)/electron-transport layer (ETL)/optionalelectron-injection layer (EIL) and finally a cathode. The cathode isformed by an aluminium layer with a thickness of 100 nm. The precisestructure of the OLEDs is shown in Table 1. The materials required forthe production of the OLEDs are shown in Table 3.

All materials are applied by thermal vapour deposition in a vacuumchamber. The emission layer here always consists of at least one matrixmaterial (host material) and an emitting dopant (emitter), which isadmixed with the matrix material or matrix materials in a certainproportion by volume by co-evaporation. An expression such asIC1:IC3:TEG1 (55%:35%:10%) here means that material IC1 is present inthe layer in a proportion by volume of 55%, IC3 is present in the layerin a proportion of 35% and TEG1 is present in the layer in a proportionof 10%. Analogously, the electron-transport layer may also consist of amixture of two materials.

The OLEDs are characterised by standard methods. For this purpose, theelectroluminescence spectra, the current efficiency (measured in cd/A),the power efficiency (measured in Im/W) and the external quantumefficiency (EQE, measured in percent) as a function of the luminousdensity, calculated from current/voltage/luminous density characteristiclines (IUL characteristic lines) assuming Lambert emissioncharacteristics, and the lifetime are determined. Theelectroluminescence spectra are determined at a luminous density of 1000cd/m², and the CIE 1931 x and y colour coordinates are calculatedtherefrom. The term U1000 in Table 2 denotes the voltage required for aluminous density of 1000 cd/m². CE1000 and PE1000 denote the current andpower efficiency respectively which are achieved at 1000 cd/m². Finally,EQE1000 denotes the external quantum efficiency at an operating luminousdensity of 1000 cd/m². The lifetime LT is defined as the time afterwhich the luminous density drops from the initial luminous density to acertain proportion L1 on operation at constant current. An expression ofL0;j0=4000 cd/m² and L1=70% in Table 2 means that the lifetime indicatedin column LT corresponds to the time after which the initial luminousdensity drops from 4000 cd/m² to 2800 cd/m². Analogously, L0;j0=20mA/cm², L1=80%, means that the luminous density drops to 80% of itsinitial value after time LT on operation at 20 mA/cm².

The data of the various OLEDs are summarised in Table 2. Examples V1-V6are comparative examples in accordance with the prior art, ExamplesE1-E37 show data of OLEDs according to the invention.

Some of the examples are explained in greater detail below in order toillustrate the advantages of the OLEDs according to the invention.

Use of Mixtures According to the Invention in the Emission Layer ofPhosphorescent OLEDs

On use as matrix materials in phosphorescent OLEDs, the materialsaccording to the invention give rise to significant improvements overthe prior art with respect to the lifetime of the components. Use ofcompounds EG1 to EG4 according to the invention in combination with thegreen-emitting dopant TEG1 enables an increase in the lifetime by morethan 200% compared with the prior art to be observed (comparison ofExamples V1 with E1, E6 and V2 with E2 as well as V3 with E3 and V4, V5with E4).

TABLE 1 Structure of the OLEDs HTL IL EBL EML HBL ETL EIL Ex. ThicknessThickness Thickness Thickness Thickness Thickness Thickness V1 SpA1HATCN SpMA1 SdT1:TEG1 (90%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm  5 nm  90nm 30 nm 10 nm 30 nm V2 SpA1 HATCN SpMA1 SdT2:TEG1 (90%:10%) ST2 ST2:LiQ(50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm V3 SpA1 HATCN SpMA1SdT3:TEG1 (90%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10nm 30 nm V4 SpA1 HATCN SpMA1 SdT4:TEG1 (90%:10%) ST2 ST2:LiQ (50%:50%) —70 nm  5 nm  90 nm 30 nm 10 nm 30 nm V5 SpA1 HATCN SpMA1 SdT5:TEG1(90%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30 nmV6 SpA1 HATCN SpMA1 SdT6:TEG1 (90%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm  5nm  90 nm 30 nm 10 nm 30 nm E1 SpA1 HATCN SpMA1 EG1:TEG1 (90%:10%) ST2ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E2 SpA1 HATCNSpMA1 EG2:TEG1 (90%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30nm 10 nm 30 nm E3 SpA1 HATCN SpMA1 EG3:TEG1 (90%:10%) ST2 ST2:LiQ(50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E4 SpA1 HATCN SpMA1EG4:TEG1 (90%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10nm 30 nm E5 SpA1 HATCN SpMA1 EG5:TER1 (92%:8%) — ST2:LiQ (50%:50%) — 90nm  5 nm 130 nm 30 nm 40 nm E6 SpA1 HATCN SpMA1 EG6:TER1 (92%:8%) —ST2:LiQ (50%:50%) — 90 nm  5 nm 130 nm 30 nm 40 nm E7 SpA1 HATCN SpMA1EG7:TEG1 (90%:10%) — ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 40 nmE8 SpA1 HATCN SpMA1 EG8:TEG1 (90%:10%) — ST2:LiQ (50%:50%) — 70 nm  5 nm 90 nm 30 nm 40 nm E9 SpA1 HATCN SpMA1 EG9:IC3:TEG1 (45%:45%:10%) IC1ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E10 SpA1 HATCNSpMA1 EG10:IC3:TEG1 (45%:45%:10%) IC1 ST2:LiQ (50%:50%) — 70 nm  5 nm 90 nm 30 nm 10 nm 30 nm E11 SpA1 HATCN SpMA1 EG11:IC3:TEG1(45%:45%:10%) IC1 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30nm E12 SpA1 HATCN SpMA1 IC1:TEG1 (90%:10%) — EG12 LiQ 70 nm  5 nm  90 nm30 nm 40 nm 3 nm E13 SpA1 HATCN SpMA1 IC1:TEG1 (90%:10%) IC1 EG13:LiQ(50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E14 SpA1 HATCN SpMA1EG14:IC3:TEG1 (65%:25%:10%) IC1 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm30 nm 10 nm 30 nm E15 SpA1 HATCN SpMA1 IC1:TEG1 (90%:10%) EG15 ST2:LiQ(50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E16 HATCN SpMA1 SpMA2EG16:L1:TEY1 (45%:45%:10%) — ST1 LiQ  5 nm 70 nm  15 nm 25 nm 45 nm 3 nmE17 SpA1 HATCN SpMA1 EG17:TEG1 (90%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm 5 nm  90 nm 30 nm 10 nm 30 nm E18 SpA1 HATCN SpMA1 EG18:IC3:TEG1(45%:45%:10%) IC1 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30nm E19 HATCN SpMA1 SpMA2 EG19:L1:TEY1 (45%:45%:10%) — ST1 LiQ 5 nm 70 nm 15 nm 25 nm 45 nm 3 nm E20 SpA1 HATCN SpMA1 IC1:TEG1 (90%:10%) EG20ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E21 SpA1 HATCNSpMA1 EG21:TEG1 (90%:10%) — ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm40 nm E22 SpA1 HATCN SpMA1 EG22:TEG1 (90%:10%) — ST2:LiQ (50%:50%) — 70nm  5 nm  90 nm 30 nm 30 nm E23 SpA1 HATCN SpMA1 IC1:TEG1 (90%:10%) —EG23:ST1 LiQ 70 nm  5 nm  90 nm 30 nm 40 nm 3 nm E24 SpA1 HATCN SpMA1EG24:TEG1 (90%:10%) — ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 30 nmE25 SpA1 HATCN SpMA1 EG25:IC3:TEG1 (50%:40%:10%) ST2 ST2:LiQ (50%:50%) —70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E26 SpA1 HATCN SpMA1 EG26:IC3:TEG1(55%:35%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30nm E27 SpA1 HATCN SpMA1 EG27:IC3:TEG1 (45%:45%:10%) ST2 ST2:LiQ(50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E28 SpA1 HATCN SpMA1IC1:TEG1 (90%:10%) IC1 EG28:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10nm 30 nm E29 SpA1 HATCN SpMA1 EG29:TER1 (92%:8%) — ST2:LiQ (50%:50%) —90 nm  5 nm 130 nm 30 nm 40 nm E30 SpA1 HATCN SpMA1 EG30:IC3:TEG1(45%:45%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30nm E31 SpA1 HATCN SpMA1 EG1:IC3:TEG1 (50%:40%:10%) ST2 ST2:LiQ (50%:50%)— 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E32 SpA1 HATCN SpMA1 EG1:IC4:TEG1(40%:45%:15%) ST2 ST2LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30nm E33 SpA1 HATCN SpMA1 EG1:IC5:TEG1 (70%:25%:5%) ST2 ST2:LiQ (50%:50%)— 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E34 SpA1 HATCN SpMA1 EG1:IC6:TEG1(45%:45%:10%) ST2 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30nm E35 SpA1 HATCN SpMA1 EG1:IC7:TEG1 (40%:50%:10%) ST2 ST2:LiQ (50%:50%)— 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm E36 SpA1 HATCN SpMA1 EG1:IC8:TEG1(30%:50%:20%) ST2 ST2:LiQ (50%:50%) — 70 nm  5 nm  90 nm 30 nm 10 nm 30nm E37 SpA1 HATCN SpMA1 EG1:L1:TEG1 (25%:55%:20%) ST2 ST2:LiQ (50%:50%)— 70 nm  5 nm  90 nm 30 nm 10 nm 30 nm

TABLE 2 Data of the OLEDs U1000 CE1000 PE1000 EQE CIE x/y at L1 LT Ex.(V) (cd/A) (lm/W) 1000 1000 cd/m² L₀: j₀ % (h) V1 3.6 51 44 13.7%0.33/0.63 20 mA/cm² 80 95 V2 4.2 50 37 14.3% 0.33/0.62 20 mA/cm² 80 10V3 4.3 55 40 14.7% 0.33/0.64 20 mA/cm² 80 15 V4 3.5 48 43 12.8%0.32/0.64 20 mA/cm² 80 190 V5 3.7 59 50 15.7% 0.33/0.64 20 mA/cm² 80 125V6 3.4 44 41 11.8% 0.31/0.65 20 mA/cm² 80 20 E1 3.5 40 36 11.6%0.33/0.62 20 mA/cm² 80 290 E2 4.3 51 37 14.5% 0.33/0.62 20 mA/cm² 80 20E3 4.4 55 39 15.0% 0.33/0.63 20 mA/cm² 80 35 E4 3.6 41 35 11.9%0.32/0.63 20 mA/cm² 80 300 E5 4.4 13 9 12.4% 0.66/0.34 4000 cd/m² 80 340E6 4.6 11 8 11.4% 0.67/0.34 4000 cd/m² 80 370 E7 3.4 59 55 15.9%0.33/0.63 20 mA/cm² 80 115 E8 3.6 56 49 15.2% 0.33/0.62 20 mA/cm² 80 125E9 3.4 62 57 16.5% 0.34/0.63 20 mA/cm² 80 240 E10 3.5 60 54 16.1%0.33/0.63 20 mA/cm² 80 350 E11 3.6 57 50 15.5% 0.33/0.63 20 mA/cm² 80290 E12 3.3 64 61 17.1% 0.33/0.63 20 mA/cm² 80 125 E13 3.7 62 53 16.5%0.34/0.63 20 mA/cm² 80 165 E14 3.3 60 57 16.7% 0.32/0.63 20 mA/cm² 80270 E15 3.5 59 53 16.0% 0 34/0.63 20 mA/cm² 80 145 E16 2.9 75 81 22.4%0.44/0.55 50 mA/cm² 90 85 E17 3.4 41 37 11.7% 0.33/0.63 20 mA/cm² 80 140E18 3.5 60 53 16.3% 0.33/0.63 20 mA/cm² 80 260 E19 2.8 77 86 23.1%0.45/0.55 50 mA/cm² 90 100 E20 3.7 59 50 15.8% 0.33/0.63 20 mA/cm² 80155 E21 3.7 55 47 14.7% 0.36/0.61 20 mA/cm² 80 135 E22 3.8 58 48 15.6%0.33/0.63 20 mA/cm² 80 140 E23 3.4 62 57 17.0% 0.31/0.64 20 mA/cm² 80130 E24 3.8 56 46 15.3% 0.33/0.63 20 mA/cm² 80 125 E25 3.6 60 52 16.0%0.35/0.62 20 mA/cm² 80 360 E26 3.7 57 48 15.2% 0.33/0.63 20 mA/cm² 80275 E27 3.6 54 47 15.5% 0.34/0.61 20 mA/cm² 80 255 E28 3.6 60 52 16.4%0.34/0.62 20 mA/cm² 80 170 E29 4.5 13 9 11.6% 0.67/0.33 4000 cd/m² 80340 E30 3.5 58 52 15.6% 0.33/0.63 20 mA/cm² 80 270 E31 3.4 59 55 15.9%0.32/0.64 20 mA/cm² 80 380 E32 3.4 61 56 16.2% 0.33/0.64 20 mA/cm² 80360 E33 3.3 59 56 15.7% 0.33/0.63 20 mA/cm² 80 335 E34 3.5 61 55 16.3%0.33/0.63 20 mA/cm² 80 355 E35 3.4 62 57 16.6% 0.31/0.64 20 mA/cm² 80340 E36 3.4 59 55 16.1% 0.33/0.63 20 mA/cm² 80 345 E37 3.3 54 51 15.0%0.32/0.63 20 mA/cm² 80 395

TABLE 3 Structural formulae of the materials for the OLEDs

HATCN

SpA1

SpMA1

LiQ

SpMA2

TER1

L1

TEY1

IC1

ST2

IC3

TEG1

IC4

IC5

IC6

IC7

IC8

SdT1

SdT2

SdT3

SdT4

SdT5

SdT6

EG1

EG2

EG3

EG4

EG5

EG6

EG7

EG8

EG9

EG10

EG11

E12

EG13

EG14

EG15

EG16

EG17

EG18

EG19

EG20

EG21

EG22

EG23

EG24

EG25

EG26

EG27

EG28

EG29

EG30

The invention claimed is:
 1. A mixture comprising at least one compoundof the formula (1a),

where the following applies to the symbols and indices used: A is oneach occurrence, identically or differently, CR or N, where a maximum oftwo groups A per ring stand for N and where A stands for C if the groupcomprising Y² is bonded at this position; X is on each occurrence,identically or differently, CR or N, with the proviso that at least onegroup X stands for N; Ar is on each occurrence, identically ordifferently, an aromatic or heteroaromatic ring system having 5 to 30aromatic ring atoms, which may be substituted by one or more radicals R;Y¹ is O, NR′, S or CR² where R¹ is phenyl; Y² is O or S; L is on eachoccurrence, identically or differently, a single bond or an aromaticring system having 5 to 30 aromatic ring atoms, which may be substitutedby one or more radicals R; R″ is phenyl; n is 0, 1, 2, 3 or 4; R isselected on each occurrence, identically or differently, from the groupconsisting of H, D, F, Cl, Br, I, CN, NO₂, N(Ar¹)₂, N(R¹)₂, C(═O)Ar¹,C(═O)R¹, P(═O)(Ar¹)₂, P(Ar¹)₂, B(Ar¹)₂, Si(Ar¹)₃, Si(R¹)₃, astraight-chain alkyl, alkoxy or thioalkyl group having 1 to 20 C atomsor a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20C atoms or an alkenyl group having 2 to 20 C atoms, each of which may besubstituted by one or more radicals R¹, where one or more non-adjacentCH₂ groups may be replaced by R¹C≡CR¹, Si(R¹)₂, C═O, C═S, C≡NR,P(═O)(R¹), SO, SO₂, NR¹, O, S or CONR¹ and where one or more H atoms maybe replaced by D, F, Cl, Br, I, CN or NO₂, an aromatic or heteroaromaticring system having 5 to 40 aromatic ring atoms, which may in each casebe substituted by one or more radicals R¹, an aryloxy or heteroaryloxygroup having 5 to 40 aromatic ring atoms, which may be substituted byone or more radicals R¹, or an aralkyl or heteroaralkyl group having 5to 40 aromatic ring atoms, which may be substituted by one or moreradicals R¹; two substituents R which are bonded to the same carbon atomor to adjacent carbon atoms may optionally form a monocyclic orpolycyclic, aliphatic, aromatic or heteroaromatic ring system here,which may be substituted by one or more radicals R¹; Ar¹ is on eachoccurrence, identically or differently, an aromatic or heteroaromaticring system having 5 to 30 aromatic ring atoms, which may be substitutedby one or more non-aromatic radicals R¹; two radicals Ar¹ which arebonded to the same N atom, P atom or B atom may also be bridged to oneanother here by a single bond or a bridge selected from N(R¹), C(R¹)₂, Oor S; R¹ is selected on each occurrence, identically or differently,from the group consisting of H, D, F, CN, an aliphatic hydrocarbonradical having 1 to 20 C atoms or an aromatic or heteroaromatic ringsystem having 5 to 30 aromatic ring atoms, in which one or more H atomsmay be replaced by D, F, Cl, Br, I or CN and which may be substituted byone or more alkyl groups, each having 1 to 4 carbatoms; two or moreadjacent substituents R¹ may form a mono- or polycyclic, aliphatic ringsystem with one another here; and at least one further compound, whereinthe further compound is a matrix material and wherein the matrixmaterial is a hole-transporting compound.
 2. The mixture according toclaim 1, wherein X is on each occurrence N.
 3. The mixture according toclaim 1, wherein Y¹ is O.
 4. The mixture according to claim 1, whereinY¹ is S.
 5. The mixture according to claim 1, wherein Y² is O.
 6. Themixture according to claim 1, wherein Y² is S.
 7. The mixture accordingto claim 1, wherein the hole transporting compound is a carbazolederivative.
 8. The mixture according to claim 7, wherein the carbazolederivative is a biscarbazole.
 9. The mixture according to claim 1,wherein the compound of formula (1a) is selected from the group ofcompounds


10. An organic electroluminescent device comprising the mixtureaccording to claim
 1. 11. An organic electroluminescent devicecomprising the mixture according to claim
 8. 12. An organicelectroluminescent device comprising the mixture according to claim 9.13. An organic electroluminescent device comprising the mixtureaccording to claim 1 wherein the mixture is employed in an emittinglayer, in combination with a phosphorescent dopant.
 14. An organicelectroluminescent device comprising the mixture according to claim 8wherein the mixture is employed in an emitting layer, in combinationwith a phosphorescent dopant.
 15. An organic electroluminescent devicecomprising the mixture according to claim 9 wherein the mixture isemployed in an emitting layer, in combination with a phosphorescentdopant.
 16. A mixture comprising at least one compound of the formula(1a),

where the following applies to the symbols and indices used: A is oneach occurrence, identically or differently, CR or N, where a maximum oftwo groups A per ring stand for N and where A stands for C if the groupcomprising Y² is bonded at this position; X is on each occurrence,identically or differently, CR or N, with the proviso that at least onegroup X stands for N; Ar is on each occurrence, identically ordifferently, an aromatic or heteroaromatic ring system having 5 to 30aromatic ring atoms, which may be substituted by one or more radicals R;Y¹ is S; Y² is O or S; L is on each occurrence, identically ordifferently, a single bond or an aromatic ring system having 5 to 30aromatic ring atoms, which may be substituted by one or more radicals R;R″ is phenyl; n is 0, 1, 2, 3 or 4; R is selected on each occurrence,identically or differently, from the group consisting of H, D, F, Cl,Br, I, CN, NO₂, N(Ar¹)₂, N(R¹)₂, C(═O)Ar¹, C(═O)R¹, P(═O)(Ar¹)₂,P(Ar¹)₂, B(Ar¹)₂, Si(Ar¹)₃, Si(R¹)₃, a straight-chain alkyl, alkoxy orthioalkyl group having 1 to 20 C atoms or a branched or cyclic alkyl,alkoxy or thioalkyl group having 3 to 20 C atoms or an alkenyl grouphaving 2 to 20 C atoms, each of which may be substituted by one or moreradicals R¹, where one or more non-adjacent CH₂ groups may be replacedby R¹C≡CR¹, Si(R¹)₂, C═O, C═S, C≡NR, P(═O)(R¹), SO, SO₂, NR¹, O, S orCONR¹ and where one or more H atoms may be replaced by D, F, Cl, Br, I,CN or NO₂, an aromatic or heteroaromatic ring system having 5 to 40aromatic ring atoms, which may in each case be substituted by one ormore radicals R¹, an aryloxy or heteroaryloxy group having 5 to 40aromatic ring atoms, which may be substituted by one or more radicalsR¹, or an aralkyl or heteroaralkyl group having 5 to 40 aromatic ringatoms, which may be substituted by one or more radicals R¹; twosubstituents R which are bonded to the same carbon atom or to adjacentcarbon atoms may optionally form a monocyclic or polycyclic, aliphatic,aromatic or heteroaromatic ring system here, which may be substituted byone or more radicals R¹; Ar¹ is on each occurrence, identically ordifferently, an aromatic or heteroaromatic ring system having 5 to 30aromatic ring atoms, which may be substituted by one or morenon-aromatic radicals R¹; two radicals Ar¹ which are bonded to the sameN atom, P atom or B atom may also be bridged to one another here by asingle bond or a bridge selected from N(R¹), C(R¹)₂, O or S; R¹ isselected on each occurrence, identically or differently, from the groupconsisting of H, D, F, CN, an aliphatic hydrocarbon radical having 1 to20 C atoms or an aromatic or heteroaromatic ring system having 5 to 30aromatic ring atoms, in which one or more H atoms may be replaced by D,F, Cl, Br, I or CN and which may be substituted by one or more alkylgroups, each having 1 to 4 carbatoms; two or more adjacent substituentsR¹ may form a mono- or polycyclic, aliphatic ring system with oneanother here; and at least one further compound, wherein the furthercompound is a matrix material.
 17. A mixture comprising at least onecompound of the formula (1a),

where the following applies to the symbols and indices used: A is oneach occurrence, identically or differently, CR or N, where a maximum oftwo groups A per ring stand for N and where A stands for C if the groupcomprising Y² is bonded at this position; X is on each occurrence,identically or differently, CR or N, with the proviso that at least onegroup X stands for N; Ar is on each occurrence, identically ordifferently, an aromatic or heteroaromatic ring system having 5 to 30aromatic ring atoms, which may be substituted by one or more radicals R;Y¹ is O, NR¹, S or CR² where R¹ is phenyl; Y² is S; L is on eachoccurrence, identically or differently, a single bond or an aromaticring system having 5 to 30 aromatic ring atoms, which may be substitutedby one or more radicals R; R″ is phenyl; n is 0, 1, 2, 3 or 4; R isselected on each occurrence, identically or differently, from the groupconsisting of H, D, F, Cl, Br, I, CN, NO₂, N(Ar¹)₂, N(R¹)₂, C(═O)Ar¹,C(═O)R¹, P(═O)(Ar¹)₂, P(Ar¹)₂, B(Ar¹)₂, Si(Ar¹)₃, Si(R¹)₃, astraight-chain alkyl, alkoxy or thioalkyl group having 1 to 20 C atomsor a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 20C atoms or an alkenyl group having 2 to 20 C atoms, each of which may besubstituted by one or more radicals R¹, where one or more non-adjacentCH₂ groups may be replaced by R¹C≡CR¹, Si(R¹)₂, C═O, C═S, C≡NR,P(═O)(R¹), SO, SO₂, NR¹, O, S or CONR¹ and where one or more H atoms maybe replaced by D, F, Cl, Br, I, CN or NO₂, an aromatic or heteroaromaticring system having 5 to 40 aromatic ring atoms, which may in each casebe substituted by one or more radicals R¹, an aryloxy or heteroaryloxygroup having 5 to 40 aromatic ring atoms, which may be substituted byone or more radicals R¹, or an aralkyl or heteroaralkyl group having 5to 40 aromatic ring atoms, which may be substituted by one or moreradicals R¹; two substituents R which are bonded to the same carbon atomor to adjacent carbon atoms may optionally form a monocyclic orpolycyclic, aliphatic, aromatic or heteroaromatic ring system here,which may be substituted by one or more radicals R¹; Ar¹ is on eachoccurrence, identically or differently, an aromatic or heteroaromaticring system having 5 to 30 aromatic ring atoms, which may be substitutedby one or more non-aromatic radicals R¹; two radicals Ar¹ which arebonded to the same N atom, P atom or B atom may also be bridged to oneanother here by a single bond or a bridge selected from N(R¹), C(R¹)₂, Oor S; R¹ is selected on each occurrence, identically or differently,from the group consisting of H, D, F, CN, an aliphatic hydrocarbonradical having 1 to 20 C atoms or an aromatic or heteroaromatic ringsystem having 5 to 30 aromatic ring atoms, in which one or more H atomsmay be replaced by D, F, Cl, Br, I or CN and which may be substituted byone or more alkyl groups, each having 1 to 4 carbatoms; two or moreadjacent substituents R¹ may form a mono- or polycyclic, aliphatic ringsystem with one another here; and at least one further compound, whereinthe further compound is a matrix material.